Racemic dihydro-pge{11 {11 and related compounds

ABSTRACT

1. A racemic compound of the formula WHEREIN R is selected from the group consisting of hydrogen and methyl, R1 is selected from the group consisting of hydrogen and the acyl radical of a hydrocarbon carboxylic acid containing one to 12 carbon atoms, inclusive, R2 is selected from the group consisting of hydrogen and methyl, with the proviso that not more than one R2 can be methyl in a given side chain, R3 is selected from the group consisting of hydrogen and an alkyl radical containing from one to 12 carbon atoms, inclusive, R4 is an alkyl radical containing one to eight carbons, inclusive, N1 IS AN INTEGER SELECTED FROM THE GROUP CONSISTING OF 0 AND 1, AND WHEN R3 is hydrogen the pharmacologically acceptable salts thereof.

[ 1 Jan. 16,1973

541 RACEMIC DIHYDRO-PGE, AND

RELATED COMPOUNDS [75] lnventors: Philip F. Beal, Ill; Frank H. Lincoln, Jr.; John C. Babcock, all of Kalamazoo, Mich.

[73] Assignee: The Upjohn Company, Kalamazoo,

Mich,

[22] Filed: April 6, 1970 {21] Appl.No.: 31,062

Related US. Application Data [62] Division of Ser. No. 541,477, April 11, 1966, Pat.

[52} US. Cl ..260/468 D, 260/468 K, 260/488 R, 260/514 D, 260/514 K, 260/410 [51] lnt. Cl. ..C07c 61/36, C07c 69/74 [58] Field of Search ..260/5 14, 468

156] References Cited UNITED STATES PATENTS 3,296,091 1/1967 Bell] et al 195/30 Primary E.\'aminer Lorraine A. Weinberger Assistant Examiner-Robert Gerstl A!mrm'yGeorge T. Johannesen EXEMPLARY CLAIM l. A racemic compound of the formula 0 -CH-COOR;

wherein R is selected from the group consisting of hydrogen and methyl,

R, is selected from the group consisting of hydrogen and the acyl radical of a hydrocarbon carboxylic acid containing one to 12 carbon atoms, inclusive,

R is selected from the group consisting of hydrogen and methyl, with the proviso that not more than one R can be methyl in a given side chain,

R is selected from the group consisting of hydrogen and an alkyl radical containing from one to 12 carbon atoms, inclusive,

R is an alkyl radical containing one to eight carbons, inclusive,

n is an integer selected from the group consisting of 0 and l,

and when R is hydrogen the pharmacologically acceptable salts thereof.

3 Claims, No Drawings 1. itAcE'MIC nmiFDRO PGE AND RELATED- COMPOUNDS I This is a division of copending application Ser. No. 541,477, filed Apr. 11, 1966, now U.S. Pat. No. 3,505,387.

This invention relates to compounds related. to prostaglandins and having prostaglandin, like activity, and to intermediates used in the manufacture of these compounds. This invention also relates to aprocess for the manufacture of dihydroprostaglandin E, (dihydro PGE and related compounds.

The term prostaglandin is used broadly to designate a.

material, having hypotensive and smooth musclestimulating activity, obtainable from accessory genital glands, seminal fluid, and the like. Prostaglandins have been found to be present in the kidney and lung of both male and female animals and in the seminal'vesicles of the male. A crude material, designated-prostaglandin, was obtained by von Euler from extracts of such materials [Arch. Exp. Path. Pharmak, 178,78 (1934), 181 (1936), J. Physiol. 72, 74 (1931), 81, 102 (1934), 84, 21 (1935), 88, 213 (1936), Klin. Wschr. l4, 11,8L (1935)]. Recently [Acta Chemica Scandinavia 14, 19634704 (1960)] two distinct compounds designated PGE (now known as PGE,) and PGF (now. known as PGF,a) have been isolated from crude materials such as von Euler prostaglandin.

PGE contains an unsaturated, non-aromatic hydroxycarboxylic acid side chain. PGE can be selectively hydrogenated by the usual methods for saturating ethenoid double bonds, for example, hydrogenation in a.

solvent such as ethanol or acetic acid in the presence of rhodium, Raney nickel, platinum, palladium or like hydrogenation catalyst to give dihydroPGE which also exhibits prostaglandin-like activity.

The structure of PGE is as follows:

HoHrcHr-cHrcHrcHr-oHr-coH hydroxyl groupis in the 5-position.

The novel compounds of the dihydroPGE series and compounds isomeric therewith of this invention are representedby the following formulas:

and

wherein R is selected from the group consisting of hydrogen and methyl,

R, is selected from the group consisting of hydrogen and the acyl radical of hydrocarbon carboxylic acid containing one to 12 carbon atoms, inclusive,

R is selected from the group consisting of hydrogen and methyl, with the proviso that not more than one R can be methyl in a given side chain,

R is selected from the group consisting of hydrogen and an alkyl radical containing from one to 12 carbon atoms, inclusive,

R is an alkyl radical containing one to eight carbon atoms, inclusive,

n is an integer selected from the group consisting of 0, l and 2,

and n, is an integer selected from the group consistrepresents the novel processes and novel intermediates ing OH) and I. used in the production of the novel compounds of For- The following reaction scheme illustratively mulas(l)and(l'):

were

I (R2 R2 R2 on? $11-$11 wen-coon,

(Ila) (llb) R2 R2) R2 ncnr-(ou-on Pea-coon;

\ 1r carom-(11km an alkyl radical containing one to l2 carbon atoms, inclusive, R, is the acyl radical of a hydrocarbon earboxylic acid containing one to l2 carbon atoms, inclusive. n is an integer selected from the group consisting of l and 2, M is an alkali metal. and R, R,, R,, R R n and n, are defined as above. In the process of this invention all the compounds having one or more asymmetric carbon atoms can be produced as raeemic mixtures. Those racemic mixtures which are obtained can be resolved at appropriate stages by methods well known in the art, and discussed more fully below, whereupon subsequent products may be obtained as the corresponding optically pure enantiomers,

It is to be understood that the pictorial representaqm bs, c mmand F'FPFFQQ? by ma s .1 [(l2a), (l2b) and (13)] and (l'), 122'), (121)), and (l3')l, (6) (6a), (7), (7a), (8), and the compounds designated (6'), (7'), (7a') and (8') below, (9), (9 and e l lb) is to construed as inclusive of other forms includ- 45 ing enantiomers and racemates; and not to be construed as limited to the particular form shown.

The compounds embraced by Formulas (l) [(1212), (l2b) and (13)], (l) [(l2a'), (l2b') and (I3')], (8) and the compounds designated (8') below, (9), (9'), (9a), (9b), (9b'), (l0), (l0'), (lla) and (1 lb) exhibit hypotensive and smooth muscle stimulating activity. The hypotensive activity of these compounds makes them useful in-the control of hypertension in birds and mammals, including humans and valuable domestic animals, and in laboratory animals such as mice, rats and rabbits.

The compounds embraced by Formulas (l) (l2b) and (l3)], (l') [(l2a'), (l2b) and (I3)], (8) compounds designated (8') below, (9), (9'), (9a'),

activity as fertility controlling agents, central nervous system regulatory agents, saltand water-retention regulatory agents, fat metabolic regulatory agents and' 65 as serum cholesterol-lowering agents which latter activity makes said compounds useful in the prevention of the onset of atherosclerosis and also in the treatment thereof in birds and mammals, including humans and valuable domestic animals. The activity of said compounds as fat metabolic regulatory agents makes them (9b), (911'), (l0), (l0), (Ila) and (llb) also possess useful in the control of obesity.

The compounds embraced by Formulas (1) [(12a), (12b) and (13a)], (1') [(12a'),(l2b'),(13')], (8) and the compounds designated (8) below, (9), (9'), (9a), (9a'), (9b), (9b), (10), (10), (11a) and (11b) also possess anti-microbial activity.

The compounds embraced by Formulas (l) [(120), (12b) and (13a)], (1) [(12a'), (12b) and (13')] (8) and the compounds designated (8') below, (9), (9'), (9a), (9aa), (9b), (9b), (10), (10'), (11a) and (11b) are administered by intravenous infusion of isotonic saline solutions at, the rate of 0.01 to about 10, preferably about 0.1 to about 1.0 micrograms per kilogram of animal weight per minute. They may also be administered buccally, intramuscularly or by rectal suppository.

The compounds embraced by Formulas (1) [(l2a), (12b) and (13)], (1') [(12a'), (12b') and (13')] (8), and the compounds designated (8') below, (9), (9), (9a), (9a'), (9b), (9b), (10), (10), (lla) and (11b) produce pronounced changes in blood pressure and block the action of vasopressin on the bladder, altering fluid transport. Agents which counteract or block this action of prostaglandin are of great interest in clinical research. To assay large numbers of compounds for prostaglandin blocking activity requires a steady supply both for treatment of control animals and for coadministration to test animals with potential blockers. Thus, the compounds listed above can be substituted for PGE,, a costly and rare material, in laboratory studies for detecting agents which counteract or block the action of PGE,. The compounds listed above are also useful because they can be administered to laboratory animals, preferably rats, to produce a pharmacologic response similar to that produced by POE Animals so treated can then serve as test animals in the search for and study of compounds which are antagonists of PGE and of the administered compounds and which, for that reason, would be useful in blocking or terminating their effects and in blocking endogenously produced prostaglandins. For these purposes, the compounds listed above are advantageously administered to the test animal by continuous intravenous infusion in sterile saline solution, at the rate of about 0.01 to about 10, preferably 0.1 to 1.0 micrograms per kilogram of animal weight per minute and the blocking agent under study administered before or during treatment to approximately half the animals. The response is measured in each group and compared to determine the blocking action of the test compound.

In addition, the compounds embraced by Formulas (1) [(1211), (12b) and (13)], (1 [(12a'), (l2b) and (13) (8) andfii'coifiibunds designated (8) below and (11b) have a surprising and unexpected influence on animal cell growth in that they inhibit the usual tendency toward cell differentiation during growth; For example addition of small amounts of the compounds of the formulas listed above to isolated growing segments of chicken skin in a nutrient medium inhibits the formation of feather follicles. Because of that activity, the compounds are useful in experimental medicine, for example in studies of wound healing and of other medical problems involving control of cell differentiation during embryological and subsequent animal growth.

Until recently prostaglandins have been available only in milligram amounts after extraction from semen or seminal vesicle tissue. Recently a biosynthetic procedure has been developed for manufacture of prostaglandins from certain essential fatty acids. This procedure has greatly improved the availability of prostaglandin supplies and has permitted limited screening for prostaglandin-blocking agents. The biosynthetic process is, however, complex, as seminal vesicles from non-castrated rams or bulls are required, essential fatty acids are needed for substrate, and a mixture of products is often encountered, purification of which is difficult and tedious. The cost of producing prostaglandins by this method in sufficient amount to satisfy current needs is so high as to be a limiting factor in research. Thus, in addition to the purposes of this in vention stated above, e.g., the control of hypertension, fertility control, fat metabolism regulation, etc., by the compounds embraced by Formulas (1) [(l2a), (12b) and (13)] (1) [(l2a'), (12b') and (13')], (8) and the compounds designated (8') below, (9), (9a), (9a'), (9b). (9b), (10), (10'), (1 la) and (11b), it is also a purpose of this invention to provide prostaglandins and prostaglandin-like materials to substitute for natural prostaglandins in the prostaglandin antagonist assays. It is still another purpose to provide a synthetic method for preparing prostaglandins and prostaglandin-like materials in substantial amount and in good purity to provide standard materials for use in prostaglandin antagonist assays. It is a further purpose to prepare sufficient prostaglandins and prostaglandin-like materials to permit a large scale screening of large numbers of compounds in sufficient numbers of animals to obtain statistically significant biological data in prostaglandin antagonist assays. I The process of this invention comprises the followmg:

The compounds of Formula (2), e.g., cyclopentane- 1,3dione are treated with a lower alkanol, either straight or branched-chain, containing one to eight carbon atoms, inclusive, e.g., methanol, ethanol, propanol, isopropanol, butanol, tert.-butanol, hexanol, octanol, and the like, to obtain the compounds of Formula (3) e.g., 3-ethoxy-2-cyclopenten-l-one. This reaction, Reaction 8-1, is carried out in the presence of an acid catalyst, e.g., p-toluenesulfonic acid, sulfuric acid, hydrochloric acid, benzene-sulfonic acid, and Lewis acids, such as boron trifluoride, and the like, preferably p-toluenesulfonic acid, and at a temperature of from 20C. to the reflux temperature of the reaction mixture with reflux temperature being preferred. Reaction S-l can be carried out with the lower alkanol functioning as both solvent and reactant. However, it is preferred to add a reaction inert water-immiscible solvent, e.g., benzene, toluene, carbon tetrachloride and the like, preferably benzene. The compounds of Formula (3) produced by Reaction 8-1 are recovered from the reaction mixture, after neutralization of the catalyst, and purified by conventional methods, such as, for example, dilution of the reaction mixture with water, extraction with a water-immiscible solvent, such as, methylene chloride, ethyl acetate, benzene, cyclohexane, ether, toluene, and the like, removal of any unchanged starting material by washing with alkali, chromatography [using Florisil (synthetic magnesium silicate) or silica gel], thin layer chromatography, distillation, or a combination of these.

Alternatively, the compounds of Formula (3) can be used in the next reaction in a semi-pure state, thus avoiding the necessity of submitting the reaction mixture of S-l to vigorous purification procedures.

The compounds of Formula (3), e.g., 3-ethoxy-2- cyclopenten-l-one, are then treated with a lower alkyl formate in the presence of a reaction inert solvent, e.g., absolute ether, chloroform, dioxane, cyclohexane, tert.-butanol, dimethylsulfoxide, and the like, preferably absolute ether, containing if desired a small amount of a lower alkanol, e.g., ethanol, and a strong alkali metal base, e.g., sodium hydride, potassium hydride, calcium hydride, lithium hydride, sodium t-butoxide, sodium ethoxide, sodium methoxide, sodium or potassium metalate of dimethylsulfoxide, phenyllithium sodium or potassium hydroxide, sodamide, and the like, capable of supplying an alkali metal, preferably with sodium hydride, and advantageously sodium hydride dispersed in a carrier, e.g., mineral oil. This reaction, Reaction 5-2, is carried out under an inert atmosphere, preferably under a nitrogen atmosphere, at a temperature of C. to 80C., preferably at 20C. for l to 60 hours, with a reaction time of 18 hours being preferred. In carrying out Reaction 8-2 the alkyl group of the lower alkyl formate (and the alkyl group of the lower alkanol and alkali metal lower alkoxide, if these compounds are used) should be the same as R of Formula (3) to avoid the obtention of a mixture of products in which R will vary. The thus obtained compounds of Formula (4), e.g., S-hydroxymethylene-B- ethoxy-2-cyclopenten-l-one as the sodium salt, are separated from the reaction mixture by conventional techniques, e.g., precipitation, filtration, centrifugation, extraction or a combination of these.

The compounds of Formula (5) are prepared by a modified Wittig reaction. [A detailed discussion of the Wittig reaction is given by Tripett, Quart. Rev. XVll, No. 4, p. 406 (1963).] The compounds of Formula (4), e.g., the sodium salt of5-hydroxymethylene-3-ethoxy-2 -cyclopenten-l-one, are then treated with a triphenylphosphonium halide of Formula (14) below to obtain the compounds of Formula (5), e.g., ethyl 7-[4-ethoxy- 2-oxo-3-cyclopenten-l -ylidene )-3,5-heptadienoate. This reaction, Reaction 8-3, is generally carried out in an inert organic solvent, such as ether, benzene, toluene, hexane, dimethylsulfoxide, tetrahydrofuran, methylene chloride, chloroform, and the like, at temperatures between 0C. and the reflux temperature of the reaction mixture, preferably at room temperature or below, using at least one mole of a triphenylphosphonium halide of Formula 14) per mole of the compounds of Formula (4) and preferably 1.2 to 2 moles. Reaction 8-3 is carried out for a period of a few hoursto several days depending on the temperature and concentration of the reaction mixture and the specific triphenylphosphonium halide of Formula (14) used, preferably under a nitrogen atmosphere. After the reaction is substantially complete the compounds of Formula (5) are recovered from the reaction mixture in a conventional manner, for example, by evaporating the solvent from the reaction mixture or by adding water and extracting with a water-immiscible solvent. The crude product can be further purified by conventional means, such as countercurrent distribution, recrystallization, chromatography, e.g., over Florisil (synthetic magnesium silicate) or silica gel, or both, or thin-layer chromatography.

The triphenylphosphonium halides of the formula:

wherein Hal is bromine or chlorine and R R and n are defined as above are prepared by reacting a compound of the formula: 7

R2 R2 R2 HalCH(C-=C)RCOOR5 wherein R R Hal and n are defined as above, with triphenylphosphine. If desired, the compounds of Formula 15) are reacted with triphenylphosphine in the presence of an inert organic solvent, e.g., chloroform, benzene, dioxane and the like.

Reduction of the ethylenic double bond in the com pounds of Formula (5), e.g., ethyl 7-[4-ethoxy-2-oxo- 3-cyclopentenl -ylidene]-3,5-heptadienoate, without concomitant reduction of the enol ether is accomplished by hydrogenation using a hydrogenation catalyst, e.g., a palladium catalyst or a rhodium catalyst, preferably a rhodium on alumina or rhodium on carbon catalyst, to produce the compounds of Formula (6), e.g., ethyl 7-(4- ethoxy-2-oxo-3-cyclopentenl-yl)heptanoate, in the presence of an inert organic solvent, e.g., methanol, ethanol, tetrahydrofuran, and the like, with methanol being preferred. The hydrogenation, Reaction 8-4, is preferably carried out at room temperature and at atmospheric or above atmospheric pressure. This reaction, Reaction 8-4, is stopped when the theoretical amount of hydrogen for saturation of the ethylenic double bonds has been absorbed. If desired, Reaction S-4 can be carried out in the presence or absence of an alkali metal acetate, e.g., potassium acetate, and/or acetic acid. The compounds of Formula (6) are recovered by conventional means, e.g., those set forth above for the recovery of the compounds of Formula (3 If in hydrogenating the compounds of Formula (5), e.g., ethyl 7-(4-ethoxy-2-oxo-3-cyclopenten-1- ylidene)-3,5-heptadienoate, less than a theoretical amount of hydrogen is used the unsaturated side chain compounds of Formula (6a), e.g., ethyl 7-(4-ethoxy-2- oxo-3-cyclopenten-l-ylidene]heptanoate, as well as the compounds of Formula (6), e.g., ethyl 7-(4-etyoxy-2- oxo-3-cyclopenten-lyl)heptanoate, are obtained. The compounds of Formulas (6) and (63) can be separated be separated from each other, and from unreacted starting material, the compounds of Formula (5), by methods known in the art, e.g., chromatography, and the compounds of Formula (6a) can be subjected separately, if desired, to further hydrogenation, Reaction 8-4,, to convert them to the compounds of Formula (6) according to the procedures of Reaction 5-4.

The compounds of Formula (6), e.g., ethyl 7-( 4- ethoxy-2-oxo-3-cyclopenten-l-yl)heptanoate, are then converted to the compounds of Formula (7), e.g., the sodium salt of ethyl 7-[5-(hydroxymethylene)-4-ethoxy-2-oxo-3-cyclopenten-l-yl]heptanoate, Reaction S-5, using the same procedures set forth above for the conversion of the compounds of Formula (3) to the compounds of Formula (4), namely, Reaction 8-2,

The compounds of Formula (7), e.g., the sodium salt of ethyl 7-[S-(hydroxymethylene)-4-ethoxy-2-oxo-3- cyclopenten-l-yl|hep-tanoate, are then reacted with a triphenylphosphonium halide of Formula (l6) below, using a modified Wittig reaction, to obtain the compounds of Formula (8), e.g., ethyl 7-[3-ethoxy-5-oxo- 2-(3-oxooctylidene)-3-cyclopenten-l-yllheptanoate. This reaction, Reaction 8-6, is carried out according to the procedures set forth above, reaction 8-3, for the conversion of the compounds of Formula (4) to the compounds of Formula (6).

The triphenylphosphonium halides of the formula:

wherein R and Hal are defined as above are prepared by reacting an acid halide of the formula:

IIall J-R4 (17) wherein R and Hal are defined as above with methylenetriphenylphosphorane. If desired, the compounds of Formula (17) are reacted with methylenetriphenylphosphorane in the presence of an inert organic solvent, e.g., chloroform, benzene, dioxane, and the like.

Similarly, substituting compounds of the formula 0 Hal-ll-RU wherein Hal is defined as above and R is wherein R is defined as above, n is l and 2 and X is H, Ch F, Cl, and OCH for the compounds of Formula (17) is productive of the corresponding triphenylphosphonium halide otherwise corresponding to Formula l6) and the otherwise corresponding prostaglandins of Formulas (8), (8'), (9), (9'), (9a), (90'), (9b), (912), (10), (10), (Ha), (lib), (12a), (l2a), (12b), and 12b), which exhibit useful prostaglandin-like properties.

The compounds of Formulas and (8) can also he prepared by the alternate route as set forth in the reaction scheme above and described in detail immediately below.

The compounds of Formula (4), e.g., the sodium salt of 5-hydroxy-methylene-3-ethoxy-2-cyclopenten-lone, and Formula (7), e.g., the sodium salt of ethyl 7- (5-hydroxymethylene-4-ethoxy-2-oxo-3-cyclopenten-l -yl)heptanoate, are, of course, in equilibrium with the compounds of Formula (4a), e.g., S-hydroxymethylene-3-ethoxy-2-cyclopenten-1-one, and Formula (7a), e.g., ethyl 7-(5-hydroxymethylene-4-ethoxy-2-oxo-3-cyclopentene-l-yl)heptanoate, as well as the free aldehyde forms thereof, respectively. The position of equilibrium is determined by the pH and the dielectric constuntof the solution and is altered by changing them. The free enols of Formulas (4a) and can he obtained by treating the compounds of Formulas (4) and (7) with an acid, while simultaneously extracting the liberated free enol into a water immiscible solvent, e.g., ether, thus avoiding the hydrolysis of the enol ether, Reactions S-2a and 8-50. Suitable acids for these reactions are inorganic acids, e.g., hydrochloric acid, sulfuric acid, phosphoric acid, and the like, and organic acids, e.g., acetic acid, formic acid, propionic acids, and the like. The free enols of Formulas (4a) and (7a) are then isolated by removal of the solvent.

The compounds of Formulas (4a) and (7a) can be converted to the compounds of Formulas (5) and (8), respectively, by the Wittig reaction. (See the discussion by Tripett referred to above).

The compounds of Formula (4a) are reacted with Wittig reagents represented, for example, by the following formula (other phosphorus derivatives known to afford Wittig reagents, such as the diethyl phosphonates, can also be used):

wherein R R and n are defined as above. The Wittig reagents of Formula (18) are prepared by reacting a compound of Formula (15) with triphenylphosphine to obtain the triphenylphosphonium halides of Formula (14). The triphenylphosphonium halides of Formula (14) are treated with a base such as sodamide, or sodium or potassium hydride, the sodium or potassium metalate of dimethylsulfoxide, phenyl lithium, sodium or potassium hydroxide, and the like, to obtain the Wittig reagents of Formula l 8). At least one mole of Wittig reagent is used per mole of the compounds of Formula (4a), and preferably from 2 to l0 moles of Wittig reagent is used. This reaction, Reaction S-3a, is generally carried out according to the procedures set forth above for the conversion of the compounds of Formula (4 to the compounds of Formula (5), Reaction 8-3.

The compounds of Formula (70) are reacted with Wittig reagents represented, for example, by the fol lowing formula (other phosphorus derivatives known wherein R is defined as above. The Wittig reagents of Formula (19) are prepared by reacting an acid halide of Formula (17) with methylenetriphenylphosphorane to obtain the triphenylphosphonium halide of Formula (16). The triphenylphosphonium halides of Formula (16) are treated with a base such as sodamide, or sodium or potassium hydride, the sodium or potassium metalate of dimethylsulfoxide, phenyl lithium, sodium or potassium hydroxide, and the like to obtain the Wittig reagent is used per mole of the compounds of Formula (7a), and preferably from 2 to moles of Wittig reagent is used. This reaction, Reaction S-6a, is generally carried out according to the procedures set forth above for the conversion of the compounds of Formula (4) to the compounds of Formula (5), Reaction S-3.

The compounds of Formula (8), e.g., ethyl 7[3- ethoxy-5oxo-2-(3-oxooctylidene )-3-cyclopenten-l-yl] heptanoate, are then hydrogenated, Reaction S-7, to obtain compounds of Formula (9), e.g., ethyl 7-(3- ethoxy-5-oxo-2(3-oxooctyl)-3-cyclopenten-l-yl]heptanoate. Reaction 5-7 is carried out according to the procedures set out above, Reaction S-4, for the conversion of the compounds of Formula (5) to the compounds of Formula (6).

The compounds of Formula (9), are then treated with an acid, e.g., p-toluenesulfonic acid, sulfuric acid, hydrochloric acid, benzenesulfonic acid, and Lewis acids, such as boron trifluoride, and the like, in the presence of an alkanol of the formula R OH, wherein R is defined as above, to give a mixture comprising the compounds of Formulas (9) and (9'), Reaction S-8. Thus, for example, treating ethyl 7-[3-ethoxy-5-oxo-2- (3-oxooctyl)-3-cyclopenten-l-yl]heptanoate (9) with p-toluenesulfonic acid in the presence of ethanol is productive of a mixture comprising the starting material and ethyl 7-[5-ethoxy-3-oxo-2-(3-oxooctyl)-4- cyclopenten-l-yl]heptanoate (9'). Reaction S-8 is carried out at a temperature of C. to 60C. for l to 72 hours, preferably at about 25C. for 16 hours. If desired, the compounds of Formula (9) and (9') obtained in Reaction S-8 can be purified and separated by conventional means, e.g., those given above for the purification of the compounds of Formula (3).

The compounds of Formula (9) can-also be treated with an acid, e.g., p-toluenesulfonic acid, sulfuric acid, hydrochloric acid, benzenesulfonic acid, and Lewis acids, such as boron trifluoride, and the like, in the presence of benzyl alcohol and at a temperature of 15C. to 60C., preferably at 25C., for l to 72 hours, preferably 16 hours, to obtain the compounds of Formulas (9a) and (90), Reaction S-8a. Thus, for example, treating ethyl 7-[3-ethoxy-5-0xo-2-(3-oxooctyl)-3- cyclopenten-l-yllheptanoate (9) with p-toluenesulfonic acid in the presence of benzyl alcohol according to the condition of Reaction S-8a is productive of a mixture comprising ethyl 7-[3-benzyloxy-5-oxo-2-(3- oxooctyl)-3-cyclopenten-l-yl]heptanoate (9a) and ethyl 7-[5-benzyloxy-3-oxo-2-(3-oxooctyl)-4- cyclopentene-l-yl]heptanoate (90). If desired the compounds of Formulas (9a) and (9a') obtained in Reaction 8a can be purified and separated by convention means, e.g., those given above for the purification of the compounds of Formula (3).

The compounds of Formula (9) can also be treated with an acid, e.g., p-toluenesulfonic acid, sulfuric acid, hydrochloric acid, benzenesulfonic acid, and Lewis acids, e.g., boron trifluoride, and the like, in presence of benzyl alcohol and at a temperature of 60C. to 120C., preferably at C., for 6 to 48 hours, preferably 24 hours, to obtain the compounds of Formulas (9b) and (9b'), Reaction S-8b. Thus, for example, treating ethyl 7-[3-ethoxy-5-oxo-2-(3-oxooctyl)-3- cyclopenten-l-yllheptanoate (9) with p-toluenesulfonic acid in the presence of benzyl alcohol according to the conditions of Reaction S-8b is productive of a mixture comprising benzyl 7-[3-benzyloxy-5-oxo-2-(3- oxooctyl)-3-cyclopenten-l-yl]heptanoate (9b) and benzyl 7-[5-benzyloxy-3-oxo-2-(3-oxooctyl)-4- cyclopenten-l-yl]heptanoate (9b'). If desired the compounds of Formula (9b) and (9b') obtained in Reaction 8b can be purified and separated by conventional means, e.g., those given above for the purification of the compounds of Formula (3).

The compounds of Formulas (8), (6) and (6a) can also be treated with an acid in the presence of an alkanol having the formula R OH according to procedures described above for Reaction S-8 to obtain a mixture comprising the starting material and the isomers thereof, hereinafter designated the compounds of (8'), (6') and (60'). Thus, for example, treating ethyl 7-[3-ethoxy-5-oxo-2-(3-oxooctylidene)-3- cyclopentenl -yl]heptanoate (8 ethyl 7-( 4-ethoxy-2-oxo-3-cyclopentenl -yl )heptanoate (6), and ethyl 7-(4-ethoxy-2-oxo-3-cyclopenten-l-ylidene)heptanoate (6a), is productive of mixtures which comprises the original starting material and the corresponding isomer thereof, for example, ethyl 7- [5-ethoxy-3-oxo-2-(3-oxooctylidene)-4-cyclopentenl-yllheptanoate (8'), ethyl 7-( 2-ethoxy-4-oxo-2-cyclopentenl -yl)heptanoate (6), and ethyl 7-(2-ethoxy-4-oxo-2-cyclopenten-l-ylidene)heptanoate (6a). If desired the compounds of Formula (8) and the compounds designated (8), the compounds of Formula (6) and the compounds designated (6), and the compounds of Formula (6a) and the compounds designated (6a'), can be purified and separated by conventional means, e.g., those given above for the purification of the compounds of Formula (3).

When the compounds of Formulas 6, 6a, 8 and 9 are isomerized with acid in an aqueous solvent mixture, hydrolysis of the enol ether can take place. The products on alkylation give the corresponding mixtures ofisomers, 6 and 6', 6a and 6a, 8 and 8', 9 and 9'.

It is to be understood that the compounds of Formulas (6), (6a), (8), (9), (9a) and (9b), as well as their corresponding isomers, i.e., the corresponding primed compounds, can be used as separate entities in subsequent reactions. It is also to be understood that mixtures of the compounds of Formulas (6), (6a), (8), (9), (9a) and (9b) with their corresponding isomers, the corresponding primed compounds, can also be used in subsequent reactions because of their ultimate conversion to the compounds of Formulas (11a) and (1 lb) below.

The compounds of Formulas (9), (9a) and (9b), and (9'), (9a') and (9b') are then treated with a reducing agent, e.g., lithium tri-tert.-butoxyaluminum hydride,

lithium aluminumtrimethoxy hydride, sodium borohydride, potassium borohydride, diborane, and the like, to produce the compounds of Formulas (l) and This reaction, Reaction 8-9, is conducted in an inert organic solvent, e.g., methanol, ethanol, tert.-bu- 5 tanol, tetrahydrofuran, dioxane, and the like, for sodium or potassium borahydride and tetrahydrofuran dioxane and the like for lithium tri-tert.-butoxyaluminum hydride, preferably at about room temperature for a period of several hours and with a slight excess of reducing agent. The product is recovered in a conventional manner, for example, by first destroying excess reducing agent, usually by adding a dilute organic acid,

(e.g., dilute acetic or formic acid), then promptly experchloric acid, phosphoric acid, p-toluene-sulfonic acid, trifluoroacetic acid, and the like, preferably dilute sulfuric acid, while maintaining an inert atmosphere, preferably a nitrogen atmosphere, to obtain the com pounds of Formula (I la). This reaction, Reaction S- 10, is carried out in the presence of an inert organic solvent, e.g., tetrahydrofuran, dioxane, acetone, and the like, preferably tetrahydrofuran, at a temperature of 5C. to 60C. for l to 48 hours, depending on the concentration of acid used. The compounds of Formula (1 la) are generally obtained directly in relatively pure state but may be further purified if desired by conventional procedures, e.g., those set out above for the purification and recovery of the compounds of Formula (3). Thus, for example, ethyl 7-[3-ethoxy-S-oxo-2-(3- hydroxyoctyl)-3-cyclopenten-l -yl]heptanoate (l0, R 7=R =ethyl) of ethyl 7-[5-ethyT-3 oxo-i G liydroxyoctyl)-4-cyclopenten-l-yl]heptanoate (lO, R R =ethyl), or mixtures thereof, are converted to ethyl 7- [3,5-dioxo-2-(3-hydroxyoctyl) tanoate (1 la).

The compounds of Formula (1 la) are also obtained by hydrogenating the compounds of Formula (10) and (10'), wherein R =benzyl and R =alkyl containing one to 12 carbon atoms, inclusive, until one equivalent of hydrogen is absorbed in the presence of a hydrogenation catalyst, preferably palladium on charcoal catalyst. This reaction, Reaction S-lOa, is generally carried out at atmospheric pressure and 20C., although higher and lower pressures and temperatures are operable. Thus, for example, ethyl 7-[3-benzyloxy-5-oxo-2-(3-hydroxyoctyl)-3-cyclopenten-l-yl]heptanoate (l0, R -be nzyl, R,,=ethyl), or ethyl 7-[5-benzyloxy-3-oxo-2-(3- hydroxyoctyl )-4-cyclopenten-l -yl lheptanoate R =benzyl, R,,=ethyl) or mixtures thereof, are converted to ethyl 7-[3,5-dioxo-2-(3-hydroxyoctyl)cyclopent-l-yl lheptanoate l la).

7-[5-ethoxy-3-oxo-2-(3-oxooctyl)-4- 20 cyclopent-l-yl1hep- 50 The compounds of Formula (llb) are obtained by hydrogenating the compounds of Formula (10) and (10), wherein R =R =benzyl, until two equivalents of hydrogen is absorbed in the presence of a hydrogenation catalyst, preferably a palladium on charcoal catalyst. This reaction, Reaction S-lOa,, is carried out according to the procedures set forth above for Reaction S-lOa. Thus, for example, benzyl 7-[3-benzyloxy- 5-oxo-2-( 3-hydroxyoctyl )-3-cyclopentenl -yl heptanoate (l0, R =R =benzyl) or benzyl7-[5-benzyloxy- 3-oxo-2-(3-hydroxyoctyl)-4-cyclopenten-l-yl]heptanoate (10', R =R =benzyl), or mixtures thereof, are converted to 7[3,5-dioxo-2-(3-hydroxyoctyl)cyclopent-l-yl]heptanoic acid 1 lb).

The compounds of Formulas and (1 1b) are represented and named as B-dioxo compounds. However, it is to be understood that, like the compounds of Formulas 4a and 70, they also exist in the tautomeric enolic form and it is to be further understood the compounds of Formulas (lla) and (1 lb) as represented and named above, are inclusive of their tautomeric enolic forms.

The compounds of Formulas (lla) and (llb) are then hydrogenated to obtain the compounds of Formulas (l2a) and (l2a), and 12b) and (l2b'), respectively. This reaction, Reaction S-ll, is carried out in a manner similar to that described above for the conversion of the compounds of formula (5) to the compounds of Formula (6), Reaction S-4, except that rhodium on a support, such as carbon or alumina, is preferred as the catalyst and an acetate buffer, e.g., an alkali metal acetate, such as potassium acetate, or an alkali metal acetate in acetic acid, is preferably present in the inert organic solvent. Thus, for example, ethyl 7- [3,5-dioxo-2-(3-hydroxyoctyl)cyclopentl-yl]heptanoate (lla) is converted to ethyl 7-[3-hydroxy-5- oxo-2-( 3-hydroxyoctyl )cyclopentl -yl ]heptanoate (12a) and .ethyl 7-[5-hydroxy-3-oxo-2-(3-hydroxyoctyl)cyclopent-l-yl]heptanoate (l2a) and 7-[3,5- dioxo-2-(3-hydroxyoctyl)cyclopenten-l-yl]heptanoic acid (llb) is converted to 7-[3-hydroxy-5-oxo-2-(3 hydroxyoctyl)cyclopent-1-yl]heptanoic acid (l2b) and 7-[5-hydroxy-3-oxo-2-( 3 -hydroxyoctyl )cyclopentl yl]heptanoic acid 12b).

It has been found that occasionally the hydrogen uptake ceases before completion in Reaction S-1 1. Additional catalyst is then added and hydrogenation continued until the hydrogenation is completed. This step is of particular importance to this invention as it has been found that the reduction of the compounds of Formulas (11a) and (llb) with borohydride or aluminum hydride reducing agents does not produce the desired product. Further, the desired products, the compounds of Formulas (l2a), (l2a'), (12b) and (l2b') are B-hydroxyketones and decompose readily under inappropriate reaction conditions.

Thus, reduction of 3-ethoxy-2-cyclopenten-l-one 0 with sodium borohydride is known to produce 3-ethoxy-2-cyclopenten-l-ol and subsequent mild acid hydrolysis affords cyclopentenone but no 3-hydroxycyclopentanone. Similarly, reduction of 3-ethoxy-2-cyclohexenone with sodium borohydride is known to produce 3- ethoxy-Z-cyclohexenol and subsequent mild acid hydrolysis affords cyclohexenone but no 3-hydroxycyclohexanone. Using the above-described conditions,

we have found that 3-benzyloxy-2-cyclo-penten-l-one can be hydrogenolyzed under the conditions of step lOa using a palladium catalyst and the resulting cyclopentane-l,3-dione reduced under the conditions of step ll using a rhodium catalyst preferably in the presence of sodium acetate and acetic acid to produce 3-hydroxycyclopentanone. Similarly, 3-benzyloxy-2- cyclohexen- I -one affords 3-hydroxycyclopentanone.

Alternatively the compounds of Formulas (12a) and (l2a') are obtained by hydrogenating the compounds of Formulas (l0, R =benzyl, R,,=alkyl) and (10', R benzyl, R,,=alkyl) in the presence of the palladium catalyst, followed by further hydrogenation in the presence of the rhodium catalyst, without isolation of the compounds of Formulas 1 la) and (1 lb). Similarly the compounds of Formulas 12b and 12b are obtained by hydrogenating the compounds of Formulas 10 R.=iz.'="5en'zyi ahd'1'0 (R 7 =Rt=benzyl). It should be noted that when R =benzyl and Rg=alkyl, one equivalent of hydrogen is absorbed during the palladium hydrogenation and the products obtained are the compounds of Formulas (12a) and (l2a'), while when R, and R,,=benzyl, 2 equivalents of hydrogen are absorbed during the palladium hydrogenation and the products obtained are the compounds of Formulas (12b) and(l2b).

The compounds'of Formulas (12a) and (12b) can be acylated to yield the corresponding acylates, the compounds of Formula l3) and the compounds of Formulas (l2a') and (l2b') can be acylated to yield the corresponding acylates, the compounds of Formula (l3'). The acylation, Reaction 8-12, is carried out by reacting the starting material with an acid anhydride or acid chloride at a temperature of C. to 60C. for one to 30 hours, with 20C. and 16 hours being preferred. Advantageously, the reaction can be carried out in the presence of a tertiary amine, e.g., pyridine, triethylamine, quinoline, lutidine, and the like, preferably pyridine. The products are recovered by conventional means.

The compounds of Formulas l0) and can also by acylated to obtain their corresponding acylates using the conditions described above for Reaction S- 12.

The compounds of Formulas (l2b), (l2b'), (l3, R =hydrogen), (l3', R -hydrogen) and (l lb) can be transformed to pharmacologically acceptable salts by neutralization with appropriate amounts of the corresponding inorganic or organic base. Pharmacologically acceptable cations can be the cationic form of a metal, ammonia, or an amine, or can be quaternary ammonium ions. Especially preferred metal cations are those derived from the alkali metals, e.g., lithium, sodium, and potassium, and from the alkaline earth metals, e.g., magnesium, calcium, strontium, and barium, although the cationic form of other metals, e.g., aluminum, zinc, iron, and silver, are within the scope of this invention. Pharmacologically acceptable amines can be derived from primary, secondary, or tertiary amines. Examples of suitable amines are methylamine, dimethylamine, trimethylamine, ethyl amine, dibutylamine, triisopropylamine, N-methylhexylamine, decylamine, allylamine, crotylamine, cyclopentylamine, dicyclopentylamine, ephedrine, phenylephrine, epinephrine, procaine, and the like. Examples of suitable harmacologically acceptable quaternary ammonium cations are tetramethylammonium, tetraethylammonium, benzyltrimethylammonium, phenyltriethylammonium, and the like.

These transformations to salts can be carried out by a variety of procedures known in the art to be generally useful for the preparation of inorganic. i.e., metal or ammonium, salts, amine acid addition salts, and quaternary ammonium salts. The choice of procedure will depend in part upon the solubility characteristics of the particular salt to be prepared. In the case of the inorganic salts, it is usually suitable to dissolve the selected acid in water containing the stoichiometric amount of a hydroxide, carbonate, or bicarbonate corresponding to the inorganic salt desired. Advantageously, the reaction is carried out in the presence of an inert organic solvent, e.g., methanol, ethanol, dioxane, and the like. For example, such use of sodium hydroxide, sodium carbonate, or sodium bicarbonate gives a solution of the sodium. salt. Evaporation of the water or addition of a water-miscible solvent of moderate polarity, for example, a lower alkanol or a lower alkanone gives the solid inorganic salt if that form is desired.

To produce an amine salt, the selected acid can be dissolved in a suitable solvent of either moderate or lower polarity. Examples of the former are ethanol, acetone, and ethyl acetate. Examples of the latter are diethyl ether and benzene. At least a stoichiometric amount of the amine corresponding to the desired cation is then added to that solution. If the resulting salt does not precipitate, it can usually be obtained in solid form by addition of a miscible diluent of lowpolarity or by evaporation. If the amine is relatively volatile, any excess can easily be removed by evaporation. it is preferred to use stoichiometric amounts of the less volatile amines.

Salts wherein the cation is quaternary ammonium are produced by mixing the selected acid with the stoichiometric amount of the corresponding quaternary ammonium hydroxide in water solution, followed by evaporation of the water.

The compounds ofFormulas (12b) and (l2b') can be converted to their corresponding esters, the com- I pounds of Formulas (12a) and (l2a'), respectively. This reaction, Reaction S-l 3, is carried out by reacting the selected acid with a diazoalkanc, e.g., diazomethane, diazoethane, diazobutane, l-diazo-2- ethylhexane, cyclohexyldiazomethane, diazododecane, and the like. Reaction 5-13 is carried out in the presence of an inert organic solvent, e.g., methanol, diethyl ether, tetrahydrofuran, dioxane, chloroform, and the like, or a mixture thereof, preferably in a 10 percent methanol percent diethyl ether mixture at a temperature of ()"C. to 50C., with room temperature (25C.) being preferred. The products are then purified by conventional means, e.g., evaporation to residue, followed by chromatography. Thus, for example 7-[3- hydroxy-5-oxo-2-( 3-hydroxyoctyl)cyclopent-l -yl]heptanoic acid (l2b) is reacted with diazomethane to obtain methyl 7-[3-hydroxy-5-oxo-2-(3-hydroxyoctyl)cyclopent-l -yl]heptanoate 12a).

The racemic products and intermediates of this invention can be resolved into their optically active components by a number of methods of resolution well known in the art. Those compounds which are enols or free acids or capable of-being converted to free acids, e.g., 7a, 7a, 1 lb, 12b and 12b, are treated with an optically active base, e.g., cinchonine, quinine, brucine or and la-phenylethylamine to produce diastereoisomeric salts which can be separated by crystallization. Alternatively, the acid may be esterified with an optically active alcohol, e.g., dand lmenthol, estradiol 3-acetate, and the diastereoisomeric esters then resolved. In addition, the compounds containing free hydroxyl groups can be acylated with the acid chloride or anhydride of an optically active acid, or the free acid in the presence of an esterification catalyst, e.g., d-camphorsulfonic acid, a-bromocamphor-sulfonic acid, and dand l-6,6-dinitrodiphenic acid, to give diastereoisomeric esters which are resolvable by crystallization.

Resolution of the racemic prostaglandins and prostaglandin-like compounds of this invention can also be accomplished by reverse phase and absorption chromatography on an optically active support and adsorbent and by selective transformation of one isomer with a biologically-active prostaglandin transforming system, for example, the l5-dehydrogenating system present in lung such as guinea-pig, rat, and pig lung and in microorganisms such as fungi. Such transformation can be carried out by incubation or perfusion using methods well established in the art, followed by isolation and recovery of both the isomer resistant to the metabolic transformation applied, and the product formed by the enzymatic transformation.

The S-3a and S-6a reactions described above, using the Wittig reaction, have general application to compounds having the structure respectively, wherein n, n R R R R and Q are defined as above.

The sequence of steps in the process of this invention can be rearranged, and equivalent reagents can be found besides those mentioned, without departing from the spirit of the invention. Some alternative routes have been included, but to describe all possibilities would expand this disclosure needlessly. Also, where discussion of different possible isomeric intermediates would not aid in describing the invention, such discussion has been omitted. In a number of the examples which follow, nuclear magnetic resonance spectroscopy (N.M.R.) has been used along with other instrumental properties, such as infra-red (l.R.) and ultraviolet (U.V.) spectroscopy and mass spectroscopy to charac terize and define the products obtained. For discussions of N.M.R. spectroscopy and its application as a definitive measurement and identification of chemical compositions see Bhaca and Williams, Applications of N.M.R. Spectroscopy in Organic Chemistry, Holden Day (1964); L. M. Jackman, Applications of Nuclear Magnetic Resonance Spectroscopy in Organic Chemistry, Pergamon, London (1959); J. D. Roberts, Nuclear Magnetic Resonance, McGraw Hill, N. Y. (1959); Wiberg and Nest, The lnterpretation of N.M.R. Spectra, Benjamin, N. Y. (1962).

All N.M.R. data were obtained on the Varian N.M.R. Instrument, Model A-60 (run at 60 megacycles) and reported in cycles per second (cps) downfield from the standard tetramethylsilane.

The following preparations and examples illustrate the best mode contemplated by the inventors for carrying out their invention.

Preparation 1 Cyclope'ntane-l ,3-dione (2) A solution of I00 g. of 4-cyclopentene-l,3-dione in 1100 ml. of benzene and 400 ml. of absolute ethanol was hydrogenated in an automatic shaker using 0.5 g. of 5 percent rhodium on carbon catalyst. As the reduction proceeded an additional 1.0 g. of 5 percent rhodium on carbon was added. The hydrogen uptake stopped after a total of about 1 mole of hydrogen had been absorbed. The mixture containing cyclopentanel,3-dione thus-obtained was used directly in Example l, Part A, without further purification.

Preparation 2 5-Carbethoxy-2,4-pentadienyltriphenylphosphonium bromide 54.5 (0.208 mole) of triphenylphosphine and 41.4 g. (0.19 mole) of ethyl 6-bromosorbate in ml. of chloroform was mixed while cooling in an ice-bath. The reaction mixture was allowed to stand overnight under a nitrogen atmosphere at room temperature to yield a chloroform solution of 5-carbethoxy-2,4-pentadienyltriphenylphosphonium bromide.

Similarly substituting methyl 4-bromocrotonate, methyl 3-methyl-4-bromocrotonate, ethyl bromoacetate, and the like for ethyl -bromosorbate is productive of 3-carbomethoxy-2-propenyltriphenylphosphonium bromide, 3-carbomethoxy-2-methyl-Z-propenyltriphenylphosphonium bromide, carbethoxymethyltriphcnylphosphonium bromide, and the like, respectively.

Preparation 3 2-Oxoheptyltriphenylphosphonium chloride While maintaining a nitrogen atmosphere, 54 g. of methyltriphenylphosphonium bromide was suspended in l750 ml. of absolute ether and 46 g. of 31-33 percent N-butyl lithium in wax was added thereto, followed by stirring for 2 1% hours. The thus-obtained mixture was filtered through glass wool into a solution of 26 ml. of caproyl chloride in 800 ml. of absolute ether and stirred for one hour under a nitrogen atmosphere. The solvent was then removed under diminished pressure. l,000 ml. of chloroform was added to the residue followed by 500 ml. of cold dilute hydrochloric acid (50:50) and the mixture was stirred l minutes. The organic layer was separated, washed twice with water and dried over sodium sulfate, and the solvent was removed in vacuo. Commercial hexanes were added to the residue which was then stirred and decanted. This procedure was repeated two more times after which the residue was taken up in methylene chloride, poured into 700 ml. of ether and cooled to 0C. The mixed solvent was decanted and the residual material crystallized from acetone-commercial hexanes to yield 2-oxoheptyltriphenylphos-phonium chloride having a melting point of l86-l88C.

Similarly substituting acetyl chloride, propionyl chloride, butyryl chloride, valeryl chloride, benzoylchloride, phenyacetyl chloride, B-phenylpropionyl chloride, -(2'-tetrahydropyranyloxy )-hexanoyl chloride, 5-methyl-5-(2-tetrahydropyranyloxy)-hexanoyl chloride, and the like for caproyl chloride is productive of 2-oxopropyltriphenylphosphonium chloride, 2-oxobutyltriphenylphosphonium chloride, 2-oxopentyltriphenylphosphonium chloride, 2-oxohexyltriphenylphosphonium chloride, 2-oxo-2-phenylethyltriphenylphosphonium chloride, 2-oxo-3-phenylpropyltriphenylphosphonium chloride, 2-oxo-4-phenylbutyltriphenylphosphonium chloride, 2-oxo-6-(2-tetrahydropyranyloxy)heptyltripheny lphosphonium chloride, 2-oxo-6-methyl-6-(2'-tetrahydropyranyloxy)heptyltriphenylphos-phonium chloride, and the like, respectively. Preparation 4 S-Carbethoxy-Z,4-pentadienylidenetriphenylphos-phorane A mixture of 4.38 g. of ethyl -bromosorbate, 5.97 g. of triphenylphosphine and 25 ml. of chloroform is prepared while cooling with an ice bath and is allowed to stand in the melting ice bath for about 24 hours, then the mixture is stirred vigorously under a nitrogen atmosphere and 25 ml. of cold aqueous 5 percent sodium hydroxide is added. Stirring is continued for minutes. A deep orange-red organic phase separates, which is washed with water, dried, and concentrated by evaporation under reduced pressure to give an oil comprising 5-carbeth0xy-2,4-pentadienylidenetriphenylphosphorane.

Similarly substituting methyl 4-bromocrotonate, methyl 3-methyl-4-bromocrotonate, ethyl bromoacetate, and the like for ethyl o-bromosorbate is productive of 3-carbomethoxy-2-propenylidenetriphenylphosphorane, 3-carbomethoxy-2-methyl-2-propenylidene-triphenylphosphorane, carbethoxymethylenetriphenylphosphorane, and the like, respectively.

Preparation 5 2-Oxoheptylidenetriphenylphosphorane A suspension of 4.0 g. of 2-oxoheptyltriphenylphosphonium chloride in 200 ml. of methylene chloride is mixed with ml. of water and stirred until the solid dissolves. The mixture is then cooled in an ice bath and stirred under nitrogen while a solution of 0.3 l g. of sodium hydroxide in 5 ml. of water is added dropwise. When addition is complete, the organic phase is separated and washed with water until the washes are neutral to a pH test paper; then the methylene chloride solution is separated and evaporated under diminished pressure to give a residue comprising 2-oxoheptylidenetriphenylphosphorane.

Similarly, substituting a stoichiometrically equivalent amount of 2-oxopropyltriphenylphosphonium chloride, 2-oxobutyltriphenylphosphonium chloride, 2-oxo-2-phenylethyltriphenylphosphonium chloride, and the like, for 2-oxoheptyltriphenylphosphonium chloride is productive of 2-oxopropylidenetriphenylphosphorane, 2-oxobutylidenetriphenylphosphorane, 2-oxo-2-phenylethylidenetriphenylphosphorane, the like, respectively,

and

Example 1 Part A 3-Ethoxy-2-cyclopenten-l-one (3) The mixture containing 102 g. of cyclopentane-l,3- dione (2), 1,100 ml. of benzene and 440 ml. of ethanol, obtained according to Preparation 1, was transferred to a round-bottom flask fitted with a distillation column, water trap and a condenser, and 3.3 g. of p-toluenesulfonic acid was added thereto. The acidic mixture was heated at reflux, the aqueous azeotrope being removed from the water trap, 500 ml. being removed during a 6.5 hour period. The reaction mixture contained in the round-bottom flask was cooled and washed with five 250-ml. portions of sodium hydroxide solution saturated with sodium chloride. The organic layers from each of the 5 washings were combined and washed twice with water. Each of the aqueous washes was reextracted with methylene chloride and combined with the originally obtained combined organic layers. Following removal of the organic solvent in vacuo, the

residue containing 91.0 g. was distilled in vacuo to yield and the like,

Panouse et al., Bull. Soc. Chim. Francais, l036( l955)] for cyclopentane-l ,3-dione there is obtained 3-ethoxy- 2-methyl-2-cyclopenten-l-one (3).

In like manner, substituting an aikanol, containing one to 12 carbon atoms, inclusive, e.g., methanol, propanol, isopropanol, butanol, octanol, dodecanol, and the like, for ethanol is productive of the corresponding 3-alkoxy2-methyl compounds of Formula -g-, 3-methoxy-2-methyl-2-cyclopenten-l-one, 3-propoxy-2-methyl-Z-cyclopenten- I -one, 3-isopr0poxy-2-methyl-2-cyclopenten-l -one, 3-butoxy-2-methyl-2-cyclopenten-l-one, 3-octyloxy-2-methyl-2-cyclopenten-l-one, 3-dodecyloxy-2-methyl-Z-cyclopenten-l-one, and the like, respectively.

Example 2 Sodium salt of 5-hydroxymethylene-3- ethoxy-2-cyclopenten- 1 -one (4) A solution of 39.8 g. of 3-ethoxy-2-cyclopenten-lone (3) in 100 ml. of ethyl formate and 75 ml. of absolute ether was added dropwise to a mineral oil dispersion containing 7.5 g. of sodium hydride in 600 ml. of absolute ether and 1.0 ml. of ethyl alcohol, while stirring under a nitrogen atmosphere and cooling in an icebath. After the dropwise addition was complete, the ice-bath was removed and the reaction mixture was stirred for about 18 hours and filtered. The residue was dried in vacuo to yield 55.0 g. of the sodium salt of 5- hydroxymethylene-3-ethoxy-2-cyclopenten-l-one (4) as a light yellow powder.

Similarly substituting other 3-alkoxy and 3alkoxy-2- methyl compounds, the compounds of Formula (3), e.g., 3-methoxy-2-methyl-2-cyclopenten-l-one, 3-propoxy-2-methyl-2-cyclopenten-l-one, 3-isopropoxy-2-methyl'2-cyclopenten- 1 -one, 3-butoxy-Z-methyl-2-cyclopenten-l-one, 3-octyloxy-2-methyl-2-cyclopenten-1-one, 3-dodecyloxy-2-methyl-2-cyclopenten-l-one, and the like, respectively.

Example 2 Sodium salt of 5-hydroxymethylene-3- ethoxy-Z-cyclopenten-l-one (4) A solution of 39.8 g. of 3-ethoxy-2-cyclopenten-lone (3) in ml. of ethyl formate and 75 ml. of absolute ether was added dropwise to a mineral oil dispersion containing 7.5 g. of sodium hydride in 600 ml. of absolute ether and 1.0 ml. of ethyl alcohol, while stirring under a nitrogen atmosphere and cooling in an icebath. After the dropwise addition was complete, the ice-bath was removed and the reaction mixture was stirred for about 18 hours and filtered. The residue was dried in vacuo to yield 55.0 g. of the sodium salt of hydroxymethylene-3-ethoxy-2-cyclopenten-l-one (4) as a light yellow powder.

Similarly substituting other 3-alkoxy and 3-alkoxy-2- methyl compounds, the compounds of Formula (3), e.g., 3-methoxy-2-cyclopenten-l-one, 3-propoxy-2-cyclopenten-l-one, 3-isopropoxy-2-cyclopenten-l-one, 3-butoxy-2-cyclopenten-l-one, 3-octyloxy-2-cyclopenten- -one, 3-dodecyloxy-Z-cyclopenten- I -one and the like, and 3-methoxy-2-methyl-2-cyclopenten-1 -one, 3-ethoxy-2-methyl-2-cyclopenten-l-one, 3-propoxy-2-methyl-2-cyclopenten-l-one,

3-isopropoxy-2-methyl-2-cyclopenten-l-one, 3-butoxy-2-methyl-2-cyclopenten-l -one, 3-octyloxy-2-methyl-2-cyclopenten- 1 one, 3-dodecyloxy-2-methyl-2-cyclopenten-l-one, and the like, respectively, the corresponding alkyl formates and alcohols for 3-ethoxy-2-cyclopenten-l-one, ethyl formate and ethanol, is productive of the compounds of Formula s,

the sodium salt of 5-hydroxymethylene-3-methoxy-2- cyclopenten- 1 -one,

the sodium salt of 5-hydroxymethylene-3-propoxy-2- cyclopenten-l-one,

the sodium salt of 5-hydroxymethylene-3-isopropoxy-2 -cyclopenten- I -one,

the sodium salt of 5-hydroxymethylene-3-butoxy-2- cyclopenten-l-one,

the sodium salt of 5-hydroxymethylene-3-octyloxy-2- cyclopenten-l-one,

the sodium salt of 5-hydroxymethylene-3-dodecyloxy-2 -cyclopenten-l-one, and the like, and

the sodium salt of 5-hydroxymethylene-3-methoxy-2- methyl-Z-cyclopenten-l-one,

the sodium salt of 5-hydroxymethylene-3-ethoxy-3- methyl-2-cyclopentenl -one,

the sodium salt of 5-hydroxymethylene-3-propoxy-2- methyl-2-cyclopentenl -one,

the sodium salt of 5-hydroxymethylene-3-isopropoxy-2 -methyl-2-cyclopenten- I -one,

the sodium salt of S-hydroxymethylene-3-butoxy-2- methyl-2-cyclopenten-l-one,

the sodium salt of 5-hydroxymethylene-3-octyloxy-2- methyl-Z-cyclopenten- 1 -one,

the sodium salt of 5-hydroxymethylene-3-dodecyloxy-2 -methyl-2-cyclopenten-l-one, and the like, respectively.

Likewise, the substitution of other metal hydrides, particularly alkali metal hydrides, e.g., potassium hydride, lithium hydride, and the like, for sodium hydride, in the above reaction with the appropriate 3- alkoxy and 3-alkoxy-2-methyl compounds, the compounds of Formula (3), is productive of the corresponding metal salts, e.g., the potassium salts and the lithium salts of the 5-hydroxymethylene-3-alkoxy-2- cyclopenten-l-ones and 5-hydroxymethylene-3-alkox y-2-methyl-2-cyelopenten-l-ones of Formula (4). Example 2a 5-Hydroxymethylene-3-ethoxy-2- cyclopenten-l-one (4a) A stirred mixture of 55.0 g. of the sodium salt of 5- hydroxymethylene-3-ethoxy-2-cyclopentenl -one (3 in 500 ml. of ice water is acidified with about 30 ml. of concentrated hydro-chloric acid diluted to I00 ml. with ice. Stirring is continued for about l5 minutes, then the precipitate which has formed is separated by extraction with methylene chloride, washed with water, and dried under reduced pressure to yield S-hydroxymethyl-ene- 3-ethoxy-2-cyclopenten-l-one (4a).

Similarly substituting other compounds of Formula (3) for the sodium salt of 5-hydroxymethylene-3-ethoxy-2-cyclopenten-l-one is productive of the corresponding compounds embraced by Formula (4a) depending on the starting material used.

Example 3 Ethyl 7-(4-ethoxy-2-oxo-3-cyclopenten-1- ylidene)-3,5-heptadienoate (5) To a mixture of 0.19 moles of S-carboethoxy-2,4-

pentadienyltriphenylphosphonium bromide in ml.

of chloroform, obtained according to Preparation 2, there was added 100 ml. of chloroform and 24 g. (0.136 mole) of the sodium salt of S-hydroxymethylene-3-ethoxy-2-cyclopenten-1-one (4) with stirring under a nitrogen atmosphere which was continued for 68 hours. Then the reaction mixture was washed with water, dried and evaporated in vacuo to a gummy residue. The gummy residue was taken up in methylene chloride and poured onto a chromatographic column containing 1 kg. of Florisil (synthetic magnesium silicate). The chromatographic column was eluted with percent acetone 90 percent commercial hexanes, and the fractions collected in 1,000 ml. portions. The first several fractions eluted contained crystalline triphenylphosphine. Those later fractions which, after being taken to dryness on a rotating evaporator, gave a crystalline residue were combined. The combined residue, weighing 1 1.0, was taken up in 400 ml. of anhydrous ether, concentrated to 100 ml. and filtered to yield 7.05 g. of ethyl 7-(4-ethoxy-2-oxo- 3-cyclopenten-l-ylidene)3,S-heptadienoate (5) having a melting point of 81-87C. In a similar run the .same product, ethyl 7-(4-ethoxy-2-oxo-3-cyclopenten- 1-ylidene)-3,5-heptadienoate (5) was obtained, an analytical sample ofwhich had a melting point of 84-87C. and the following analysis:

Calcd. for C, H O C, 69.54; H, 7.30.

Found: C, 69.43; H, 7.32.

IR. (principal bands; mineral oil mull): 3090, 1735, 1680, 1645, 1615,1595, 1585,1230, 1200, 1175, 1135, 1045, 1025, 1000 cm."-

ln like manner substituting 3-carbomethoxy-2-propenyltriphenylphosphonium bromide, 3-carbomethoxy-2-methyl-2-propenyltriphenylphosphonium bromide, carbethoxymethyltriphenylphosphonium bromide, and the like, for 5-carboethoxy-2,4-pentadienyltriphenylphosphonium bromide is productive of methyl 5-(4-ethoxy-2-oxo-3-cyclopenten-1-ylidene)-3- pentenoate, methyl 3-methyl-5-(4-ethoxy-2-oxo-3-cyclopenten-1- ylidene)-3-pentenoate, ethyl 3 4-ethoxy-2-oxo-3-cyclopentenl -ylidene) propionate, and the like, respectively, the compounds of Formula (5).

Likewise substituting the salts, preferably the sodium salt, of the other 5-hydroxymethylene-3-alkoxy-2- cyclopenten-l-ones and 5-hydroXymethylene-3-alkoxy-2-methyl-2-cyclopenten-1-ones, the compounds of Formula (4), for 5-hydroxymethylene-3-ethoxy-2- cyclopenten-l-one, and reacting them with the appropriate triphenylphosphonium bromide, e.g., those named in Preparation 2, is productive of the compounds embraced by Formula (5).

Example 3a Ethyl 7-(4-ethoxy-2-oxo-3-cyclopenten-1- ylidene)-3,5-heptadienoate (5) A solution of 2.5 g. of 5-hydroxymethylene-3-ethoxy-2-cyclopenten-1-one (4a) in 35 ml. of methylene chloride is stirred under nitrogen at 20C. and 7.5 g. of 5-carbethoxy-2,4-pentadienylidenetriphenylphosphorane is added. The mixture is stirred for about 16 hours, then is concentrated under reduced pressure to give a residue which is triturated with 3-100 ml. portions of commercial hexanes and filtered to remove triphenylphosphine oxide. The filtrate is evaporated to give a residue which is dissolved in methylene chloride and poured onto a chromatographic column containing 100 g. of Florisil. The chromatographic column is eluted with 10 percent acetonepercent commercial hexanes and the fractions are collected in l00-ml. portions. The first fractions eluted contain crystalline triphenylphosphine. Those later fractions which, after being taken to dryness on a rotating evaporator, give a crystalline residue are combined, taken up in anhydrous ether, concen trated and filtered to yield ethyl 7-(4-ethoxy-2-oxo-3- cyclopenten-1-ylidene)3,5-heptadienoate.

In like manner substituting 3-carbomethoxy-Z-propenylidenetriphenylphosphorane, 3-carbomethoxy-2-methyl-2-propenylidenetriphenylphosphorane, carbethoxymethylenetriphenylphosphorane, and the like, for 5-carbethoxy-2,4-pentadienylidenetriphenylphosphorane is productive of methyl 5-(4-ethoxy-2-oxo-3-cyclopenten-1-ylidene)-3- pentenoate, methyl 3-methyl-5-(4-ethoxy-2-oxo-3- cyclopenten-l-ylidene)-3-pentenoate, ethyl 3-(4-ethoxy-2-oxo-3 cyclopenten l ylidene)propionate, and the like, respectively.

Example 4 Ethyl 7-(4-ethoxy-2-oxo-3-cyclopenten-1- yl)heptanoate (6) and ethyl 7-(4-ethoxy-2-oxo-3- cyclopenten-1-ylidene)heptanoate (6a) A solution of 2.50 g. of ethyl 7-(4-ethoxy-2-oxo-3- cyclopenten-l-ylidene)-3,5-heptadienoate (5) in 50 ml. of ethanol was hydrogenated in an atmospheric pressure hydrogenator in the presence of 0.04 g. of 5% rhodium on alumina catalyst. After 3.5 hours the hydrogenation was interrupted and an additional 0.04 g. of catalyst was added. After a total uptake of 567 ml. of hydrogen (598 ml. theoretical), hydrogenation was stopped, the total time having been 6 hours. The catalyst was removed by filtration and the solvent was removed in vacuo. The residue thus obtained was taken up in methylene chloride and poured onto a chromatographic column containing about 250 g. of Florisil (synthetic magnesium silicate). The column was developed with commercial hexanes containing increasing amounts of acetone. Those fractions eluted with 10 percent acetone- 90 percent commercial hexanes were, after evaporation of the solvent, combined to yield 1.53 g. of a product comprising ethyl 7-(4- ethoxy-2-oxo-3-cyclopenten-1-yl)heptanoate (6) and ethyl 7-(4-ethoxy-2-oxo-3-cyclopentenl -ylidene)heptanoate (6a) having the following analysis:

LR. (principal bands; mineral oil mull): 1,735, 1,670,

1,600 cm.*. The above obtained 1.530 g. of product was combined with the products of two other similar runs; and the combined product weighing 4.30 g. was taken up in 33.3 percent ethyl acetate- 66.7 percent cyclohexane and poured onto a chromatographic column containing 1 500 g. of silica gel. The chromatographic column was eluted with 33.3 percent ethyl acetate 66.7 percent cyclohexane, the fractions being taken in 200 ml. portions. The solvent was evaporated and those residues which showed an untraviolet maximum in ethanol near 240 mp. were combined to yield 2.377 g. of ethyl 7-(4- ethoxy-Z-oxo-3-cyclopenten-1-yl)heptanoate (6) having the following analysis:

LR. (principal bands; methylene chloride): 1,740,

1,700, 1,600 emf.

N.M.R.: 75 cps (triplet, J=7), 84 cps (triplet, J=7), 244 cps (overlapping quartet, J=7), 310 cps (broad singlet).

Those residues eluted later which showed infrared absorption peaks at 1,660 and 1,600 cm. and an ultraviolet maximum in ethanol near 260 mg. were combined to yield 1.16 g. of ethyl 7-(4-ethoxy-2-oxo-3- cyclopenten-lylidene)heptanoate (6a) having the following analysis:

[.R. (principal bands; mineral oil mull): 1,745, 1,715,

1,660, 1,600 emf.

N.M.R.: 74 cps (triplet, J=7), 85 cps (triplet, J=7), 134 cps (triplet), 245 cps (overlapping quartets, J=7), 312 cps (triplet, J=2), 381 cps (triplet of triplets, J=7,2).

Similarly substituting methyl -(4-ethoxy-2-oxo-3-cyclopenten-l-ylidene)-3- pentenoate,

methyl 3-methyl-5-(4-ethoxy-2-oxo-3-cyclopenten-lylidene)-3-pentenoate,

ethyl 3-(4-ethoxy-2-oxo-3-cyclopenten-lylidene)propionate, and the like,

for ethyl 7-(4-ethoxy-2-oxo-3-cyclopenten-1-ylidene)- 3,5-heptadienoate is productive of methyl 5-(4-ethoxy-2-oxo-3-cyclopenten-1-yl)pentanoate and methyl 5-(4-ethoxy-2-oxo-3-cyclopenten-lylidene)pentanoate,

methyl 3-methyl-5-(4-ethoxy-2-oxo-3-cyclopenten-lyl)pentanoate and methyl 3-methyl-5-(4-ethoxy-2-oxo-3-cyclopenten-lylidene)pentanoate, and

ethyl 3-(4-ethoxy-2-oxo-3-cyclopenten- 1 yl)propionate and ethyl 3-(4-ethoxy-2-oxo-3-cyclopenten-1- ylidene)propionate, and the like, respectively.

in like manner substituting other compounds of Formula (5) for ethyl 7-(4-eth0xy-2-oxo-3-cyclopenten-l ylidene)-3,5-heptadienoate is productive of the corresponding compounds embraced by Formulas (6) and (6a) depending on the starting material used.

Example 4a Ethyl 7-(4-ethoxy-2-oxo-3-cyclopenten-lyl)heptanoate (6) A solution of 2.50 g. of ethyl 7-(4-ethoxy-2-oxo-3- cyclopenten-l-ylidene)heptanoate (6a) in 50 ml. of ethanol is hydrogenated at room temperature at atmospheric pressure in the presence of 0.08 g. of rhodium on alumina catalyst. After about 200 ml. of hydrogen is absorbed, the hydrogenation is stopped, and the reaction mixture is filtered to remove the catalyst. The filtrate is evaporated under diminished pressure to give a residue. The residue is purified by chromatography over 250 g. of silica gel, placing the residue on the column with a small amount of methylene chloride and eluting with 100 ml. portions of 33.3 percent ethyl acetate 66.7 percent cylohexanc. The eluates are dried under diminished pressure and the residues, identified by ultraviolet absorption near 240 my. and infrared absorption bands at 1,740, 1,700, and 1,600 cm", are combined to yield ethyl 7-(4- ethoxy2-oxo-3-cyclopenten-l-yl)heptanoate (5).

In like manner substituting other compounds of Formula (6a) for 7-(4-ethoxy-2-oxo-3-cyclopenten-lylidene)heptanoate is productive of the corresponding compounds of Formula (6) depending on the starting material used.

Example 4b Ethyl 7-(2-ethoxy-4-oxo-2-cyclopenten-1- yl)heptanoate (6) A solution of 1.01 g. of ethyl 7-(4-ethoxy-2-oxo-3- cyclopenten-l-yl)heptanoate (6) and 0.05 g. of ptoluenesulfonic acid in 25 ml. of absolute ethanol was stirred under nitrogen for about 16 hours at 20C. Thin layer chromatography of a portion of the reaction mixture on a silica gel plate developed with ethyl acetate indicated the presence of two spots of nearly equal intensity the less polar of which had the same mobility as starting material (6). The reaction mixture was neutralized with saturated aqueous sodium bicarbonate solution and concentrated under vacuum to produce a residue. The residue was dissolved in methylene chloride and water. The organic solvent was separated, dried, and concentrated and the concentrated solution poured onto a chromatographic column containing g. of silica gel. The column was eluted with 2:1 cyclohexane-ethyl acetate, the fractions being taken in 50 ml. portions. The first fractions eluted, in this case fractions 15-22, exhibited an infrared absorption spec trum essentially identical to that of starting material (6) and were combined to afford 0.414 g. of recovered (6). The later fractions, in this case fractions 2334, exhibited an infrared spectrum different from starting material. They were combined and the solvent removed giving 0.335 g. of ethyl 7-(2-ethoxy-4-oxo-2- cyclopenten-1-yl)heptanoate (6) having the following analysis:

N.M.R.: 73 cps (triplet, J=7), 84 cps (triplet, J=7), 244 (overlapping quartet J=7), 310 cps (sharp singlet).

Similarly, substituting other compounds of Formula (6) such as methyl 5-(4-ethoxy-2-oxo-3-cyclopenten-lyl)pentanoate, methyl 3-methyl-5-(4-ethoxy-2-oxo-3- cyclopenten-l-yl)pentanoate, ethyl 3-(4-ethoxy-2-oxo- 3-cyclopenten-l-yl)propionate, and the like, for ethyl 7-(4-ethoxy-2-oxo-3-cyclopenten-l-yl)heptanoate is productive of methyl 5-(2-ethoxy-4-oxo-2-cyclopen ten-l-yl)pentanoate, methyl 3-methyl-5-(2-ethoxy-4- oxo-2-cyclopenten-l-yl)pentanoate, ethyl 3-(2-ethoxy- 4-oxo-2-cyclopenten-l-yl)propionate, and the like.

Similarly, substituting other alcohols, such as methanol, propanol, isopropanol, butanol, octanol, dodecanol and the like, for ethanol is productive of the corresponding enol ethers.

Similarly, substituting the compounds of Formula (6a) for ethyl 7-(4-ethoxy-2-oxo-3-cyclopenten-lyl)heptanoate is productive of the compounds designated (6a), alkyl m-(2-alkoxy-4-oxo-2-cyclopenten-l-ylidcne)alkanoates, i.e., the position isomers of the compounds of Formula (6a).

Likewise, an equivalent amount of borontrifluoride etherate or of anhydrous hydrogen chloride can be substituted for p-toluenesulfonic acid in the process of Example 4a.

Example 4c Ethyl 3-(2-ethoxy-4-oxo-2-cyclopenten-1- ylidene)propionate (60) A solution of 5.7 g. of ethyl 3-(4-ethoxy-2-oxo-3- cyclopenten-l-ylidene)propionate (6a), k f 260 m in 50 ml. of water containing 60 drops of concentrated sulfuric acid was stirred at room temperature (20) for 2 hours giving a suspension which was filtered to give 4.9 g. of a solid product which was crystallized from ethyl acetate to yield 3.4 g. of ethyl 3-(2-hydroxy- 4-oxo-2-cyclopenten-l-ylidene)propionate, m.p. 155156 with decomposition, having the following analysis:

Anal. Calcd. for G Q-1, C, 61.21; H, 6.17.

Found: C, 61.12; H, 6.19.

IR. (principal bands; mineral oil mull): 2,680, 2,500,

l,735,1,675,1,620,1,565,1,500cm..

U.V. (ethanol): 275.5 mp. (c=l7,900).

N.M.R.: 74 cps (triplet, .l=7); 175 cps (doublet, 1 2); 195 cps (doublet, J=7); 249 cps (quadruplet, J=7); 322 cps (singlet); 373 cps (triplet of triplets, .l=2,7) and 505 cps.

To a suspension of 0.85 g. of ethyl 3-(2-hydroxy-4- oxo)-2-cyclopenten-l-ylidene)propionate in 30 ml. of.

ethyl acetate was added at about 20C. a dilute ethereal solution of diazoethane, until a yellow color persisted and a few drops of acetic acid are then added to decompose excess. diazoethane. The solution was washed with saturated aqueous sodium bicarbonate, dried, and concentrated to yield ethyl 3-(2-ethoxy-4- oxo-2-cyclopentenl -ylidene )propionate (6a').

LR. (principal bands; chloroform solution): 1,765,

1,760, 1,590 cmf.

U.V. (ethanol): 268 mp. (shoulder 247 mu).

N.M.R.: 75 cps (triplet, J=7); 171 cps (doublet, 1 2); 186 cps (doublet, 1 7); 247 cps (quadruplet, J=7); 327 cps (singlet); 365 cps (triplet of triplets, .l=2,7).

In like manner, other enol ethers of Formula (6a) can be hydrolyzed selectively to their corresponding free enols and can be re-etherified with diazoethane and other diazoalkanes such as diazomethane to produce the corresponding position isomeric enol ethers of Formula (60).

Example 4d Ethyl 3-(2-ethoxy-4-oxo-2-cyclopenten-lyl)propionate (6') A solution of 1.24 g. of ethyl 3-(2-ethoxy-4-oxo-2- cyclopenten-l-yliclene)propionate (6a') in 50 ml. of ethanol was hydrogenated at atmospheric pressure in a hydrogenator in the presence of 0.06 g. of 5 percent rhodium on alumina catalyst until about 1 equivalent of hydrogen was absorbed. The reduction was stopped, the catalyst removed by filtration and the solvent removed in vacuo to give a residue. The residue was dissolved in methylene chloride, poured onto a chromatographic column containing 100 g. of Florisil, and eluted with :85 acetone-commercial hexanes.

The fractions which exhibit ultraviolet absorption at 240 my. but not at 270 m are combined and, after evaporation of the solvent, afford ethyl 3-(2-ethoxy-4- oxo-2-cyclopenten-l-yl)propionate (6) having the following analysis:

1.R. (principal bands; methylene chloride solution) 1,740, 1,700, 1,600 cmf.

N.M.R.: 74 cps (triplet, .l=7); 85 cps (triplet, 1 7);

246 cps (quartet, 1 7) and 312 cps (singlet).

Similarly, substituting other compounds of Formula (60') for ethyl 3-(2-ethoxy-4-oxo-2-cyclopenten-lylidene)propionate is productive of the corresponding compounds designated (6').

Example 5 Sodium salt of ethyl 7-(5-hydroxymethylene-4-ethoxy-2-oxo-3-cyclopentenl -yl )heptanoate (7) To a solution containing 8.46 g. of ethyl 7-(4-ethoxy- 2-oxo-3-cyclopenten-l-yl)heptanoate (6) in 20 ml. of ethyl formate and 200 ml. of absolute ether there was added a mineral oil dispersion containing 1.4 g. of sodium hydride and the reaction mixture was stirred under a nitrogen atmosphere for 66 hours. 200 ml. of absolute ether was then added to replace the bulk of the ether which had escaped during the 66 hour period. The ethereal mixture was filtered to give 9.20 g. of solids comprising the sodium salt of ethyl 7-(5-hydroxymethylene-4-ethoxy-2-oxo-3-cyclopentenl -yl )heptanoate (7).

Similarly substituting methyl 5-(4-ethoxy-2-oxo-3-cyclopenten-1-yl)pentanoate, methyl 3-methy1-5-(4-ethoxy-2-oxo-3-cyclopenten-lyl)pentanoate, ethyl 3-(4-ethoxy-2-oxo-3-cyclopenten-lyl)propionate, and the like, for ethyl 7-(4-ethoxy-2- oxo3-cyclopenten-1-yl)heptanoate is productive of the sodium salt of methyl 5-(5-hydroxymethylene-4- ethoxy-2-oxo-3-cyclopenten-lyl)pentanoate, the sodium salt of methyl 3-methyl-5-(5-hydroxymethylene-4-ethoxy-2-oxo-3-cyclopentenl -yl )pentanoate, the sodium salt of ethyl 3-(5-hydroxymethylene-4- ethoxy-2-oxo-3-cyclopenten-l-yl)propionate, and the like, respectively.

In like manner substituting other compounds of Formula (6) for ethyl 7-(4-ethoxy-2-oxo-3-cyclopenten-lyl)heptanoate is productive of the corresponding compounds embraced by Formula (7) depending on the starting material used.

Likewise, the substitution of other metal hydrides, particularly alkali metal hydrides, e.g., potassium hydride and lithium hydride for sodium hydride, in the above reaction with the compounds of Formula (6) is productive of the corresponding metal salts, e.g., the potassium salts and the lithium salts of the compounds of Formula (7 Example 5a Sodium salt of ethyl 7-(5-hydroxymethylene-2-ethoxy-4-oxo-2-cyclopentenl -yl )heptanoate (7) To a solutionof 2.82 g. of ethyl 7-(2-ethoxy-4-oxo-2- cyclopenten-l-yl)heptanoate (6) in 4.0 ml. of ethyl formate and m1. of n-pentane there was added a mineral oil dispersion containing 0.26 g. of sodium hydride and the reaction mixture was stirred under a nitrogen atmosphere at 1025C. for 66 hours. The reaction mixture was then filtered to yield 2.65 g. of solids comprising the sodium salt of ethyl 7-(5-hydroxymethylene-2-ethoxy-4-oxo-2-cyclopenten-lyl)heptanoate (7').

Similarly, substituting methyl 5-( 2-ethoxy4-oxo-2-cyclopenten-l -yl)pentanoate, methyl 3-methyl-5-(2-ethoxy-4-oxo-2-cyclopenten-1- yl)pentanoate, ethyl 3-(2-ethoxy4-oxo-2-cyclopenten-lyl)propionate, and the like for ethyl 7-(2-ethoxy-4-oxo- 2-cyclopenten-1-yl)heptanoate is productive of the sodium salt of methyl 5-(S-hydroxymethylene-2-ethoxy-4-oxo-2-cyclopentenl -yl)pentanoate, the sodium salt of methyl 3-methyl-5-(5-hydroxymethylene-2-ethoxy'4-oxo-2-cyclopenten-l -yl )pentanoate,

the sodium salt of ethyl 3-(5-hydroxymethylene-2- ethoxy-4-oxo-2-cyclopenten-l-yl)propionate, and the like, respectively.

In like manner, substituting other compounds designated (6'), i.e., the position of isomers of the compounds of Formula (6), for ethyl 7-(2-ethoxy-4-oxo-2- cyclopenten-l-yl)heptanoate is productive of the corresponding compounds designated (7), i.e., the position isomers of the compounds of Formula (7).

Likewise, the substitution of other metal hydrides, particularly alkali metal hydrides, e.g., potassium hydride, lithium hydride, and the like, for sodium hydride in the above reaction is productive of the corresponding metal salts, e.g., the potassium and lithium salts.

Example 5b Ethyl 7-(5-hydroxymethylene-4-ethoxy-2- oxo-3-cyclopenten1-yl)heptanoate (7a) A stirred mixture of 55.0 g. of the sodium salt of ethyl 7-(5-hydroxymethylene4-ethoxy-2-oxo-3- cyclopenten-l-yl)heptanoate (7) in 500 ml. of ice water is acidified with about ml. of concentrated hydrochloric acid diluted to 100 ml. with ice. Stirring is continued for about 15 minutes, then the precipitate which has formed is separated by extraction with methylene chloride, washed with water and dried under reduced pressured to yield ethyl 7-(5-hydroxymethylene-4-ethoxy-2-oxo-3-cyclopenten-l -yl)heptanoate (7a).

Similarly substituting other compounds of Formula (7) and compounds designated (7'), i.e., the position isomers of the compounds of Formula (7), for the sodiurn salt of ethyl 7-(5-hydroxymethylene-4-ethoxy-2- oxo-3-cyclopenten-l-yl)heptanoate is productive of the compounds embraced by Formula (70) and those designated (7a'), i.e., the position isomers of the compounds of Formula (7a).

Example 6 Ethyl 7-[3-ethoxy-5-oxo-2-(3-oxooctylidene)-3-cyclopenten1-yl]heptanoate 9.20 g. of solids comprising the sodium salt of ethyl 7-(5-hydroxymethylene-4-ethoxy-2-oxo-3-cyclopenten-lyl)heptanoate (7) obtained as in Example 5, was added to a suspension of 15.0 g. of 2-oxoheptyltriphenylphosphonium bromide in 250 ml. of chloroform and heated at reflux under a nitrogen atmosphere for 4 hours. The reaction mixture was then cooled, washed with water and the solvent removed. The residue was taken up in methylene chloride and poured onto a chromatographic column containing 800 g. of Florisil (synthetic magnesium silicate) and the column was developed with commercial hexanes containing increasing amounts of acetone. Those fractions exhibiting major ultraviolet absorption near 272 mu (eluted in this instance with 10 percent acetone-9O percent commercial hexanes) were, after evaporation of the sol vent, combined to yield 2.32 g. of ethyl 7-[3-ethoxy-5- oxo-2-3-oxooctylidene )-3-cyclopentenl -yl ]heptanoate (8) having the following analysis:

l.R. (principal bands; methylene chloride): 1,760,

1,720,1,615,1,590 emf. N.M.R.: 53 cps (triplet); 73, 87 cps (overlapping triplets); 140 cps (broad triplet); 172 cps (broad) 197 cps (doublet, 1 7), 218 cps (doublet, .l=7); 243 cps (overlapping quartets); 318 cps (singlet); 371 cps (triplet, J=7); 409 cps (triplet).

In like manner substituting the sodium salt of methyl 5-(5-hydroxymethylene-4- ethoxy-2-oxo-3-cyclopenten-1-yl)pentanoate,

the sodium salt of methyl 3-methyl-5-(5-hydroxymethylene-4-ethoxy-2-oxo-3-cyclopenten-1-yl)pentanoate,

the sodium salt of ethyl 3-(5-hydroxymethylene-4- ethoxy-2-oxo-3-cyclopenten-1-yl)propionate, and the like,

for the sodium salt of ethyl 7-(5-hydroxymethylene-4- ethoxy-2-oxo-3-cyclopenten-1-yl)heptanoate is productive ofmethyl 5-[3-ethoxy-5-oxo-2-(3-oxooctylidene)-3- cyclopenten-l-yl]pentanoate,

methyl 3-methyl-5-[3-ethoxy-5-oxo-2-(3-oxooctylidene)-3-cyclopentenl -yl]pentanoate, and

ethyl 3-[3-ethoxy-5-oxo-2-(3-0xooctylidene)-3- cyclopenten-l-yl]propionate, and the like, respectively.

Substituting 2-oxopropyltriphenylphosphonium chloride for 2-oxoheptyltriphenylphosphonium bromide is productive of ethyl 7-[3-ethoxy-5-oxo-2-(3-oxobutylidene )-3-cyclopenten-1-yl]heptanoate.

Similarly, substituting the salts, preferably the sodium salt of other compounds of Formula (7) for ethyl 7- (5-hydroxy-methylene-4-ethoxy-2-oxo-3-cyclopentenl-yl)heptanoate and reacting it with the appropriate triphenylphosphonium chloride, e.g., those named in Preparation 3, is productive of the corresponding compounds embraced by Formula (8) depending on the starting material and the triphenylphosphonium chloride used.

Example 6a Ethyl 7-[5-ethoxy-3-oxo-2-(3-oxooctylidene)-4-cyclopenten-l-yllheptanoate (8) 2.65 g. of solids comprising the sodium salt of ethyl 7-(5-hydroxymethylene-2-ethoxy-4-oxo-2-cyclopenten-1-yl)heptanoate (7) was added to a suspension of 4.3 g. of 2-oxoheptyltriphenylphosphonium bromide in ml. of carbon tetrachloride and the mixture was stirred-under an atmosphere of nitrogen for 16 hours at 25C., then for 2 hours at reflux. The reaction mixture was then cooled and filtered and the filtrate was concentrated to produce a residue. The residue was dissolved in 2:1 cyclohexaneethyl acetate and poured onto chromatographic column containing 400 g. of silica gel and the column was developed with 2:1 cyclohexane-ethyl acetate, the fractions being collected in 200 ml. portions. These fractions which exhibited an ultraviolet absorption maximum at 260 my. (in this case fractions 12-19) were combined and the solvent removed to afford 1.83 g. of ethyl 7-(5-ethoxy- 3-oxo-2-(3-oxooctylidene)-4-cyclopenten-1-yl)heptanoate (8' 1.R. (principal bands; methylene chloride): 1,710,

1,600, 1,580 cmf'.

U.V.: 260 my. (shoulder 247 mp.)

N.M.R.: 53 cps (broad triplet); 198 cps (doublet, 1 7); 245 cps (overlapping quartets, J=7); 314 cps (broad singlet); 364 cps (triplet, 1 7); 395 cps (triplet, 1 7).

Similarly, substituting other salts, preferably the sodium salt of other compounds designated (7), i.e., the position isomers of the compounds of Formula (7) for sodium salt of ethyl 7-(5-hydroxymethylene-2- ethoxy-4-oxo-2-cyclopenten-1-yl)heptanoate is productive of the corresponding compounds of Formu- 35 la (8'), i.e., the position isomers of the compounds of Formula (8).

Example 6b Ethyl 7-[3-ethoxy-5-oxo-2-(3-oxooctylidene)-4-cyclopenten-l -yl]heptanoate (8) A mixture of 2.5 g. of ethyl 7-(5-hydroxymethylene- 4-ethoxy-2-oxo-3-cyclopenten-l-yl)heptanoate (7a), 5.0 g. of 2-oxoheptylidenetriphenylphosphorane and 150 ml. of carbon tetrachloride is stirred under a nitrogen atmosphere for about 16 hours at 25C., then for 2 hours at reflux. The reaction mixture is then concentrated to give a residue which is taken up in methylene chloride and poured onto a chromatographic column containing 200 g. of Florisil (synthetic magnesium silicate) and the column is developed with commercial hexanes containing increasing amounts of acetone. Those fractions exhibiting major ultraviolet absorption near 272 mp. are evaporated to yield ethyl 7-[3-ethoxy-5-oxo-2-(3-oxooctylidene)-4-cyclopenten-1-y1]-heptanoate(8).

In like mannersubstituting methyl -(S-hydroxymethylene-4-ethoxy-2-oxo-3- cyclopenten-l-yl)pentanoate, methyl 3-methyl-5-(5-hydroxymethylene-4-ethoxy-2- oxo.3-cyclopenten-1-yl)pentanoate, ethyl 3-(5-hydroxymethylene-4-ethoxy-2-oxo-3- cyclopenten-lyl)propionate, and the like, for ethyl 7- (5-hydroxymethylene-4-ethoxy-2-oxo-3-cyclopenten-1 -yl)heptanoate is productive of methyl S-[3-ethoxy-5- oxo-2-(3-oxooctylidene)-3-cyclopenten-1-yl]pentanoate, methyl 3-methyl-5-{3-ethoxy-5-oxo-2-(3-oxooctylidene)-3-cyclopenten-1-yl]pentanoate, ethyl 3-[3-ethoxy-5-oxo-2-(3-oxooctylidene)-3- cyclopenten-l-yl]propionate, and the like, respectively.

In like manner substituting ethyl 7-(-5-hydroxymethylene-2-ethoxy-4-oxo-2- cyclopenten-l-yl)heptanoate (7a') and other compounds designated (7a') for ethyl 7-(5-hydroxymethylene-4-ethoxy-2-oxo-3-cyclopenten-1-yl)heptanoate (7a) is productive of ethyl 7-[5-ethoxy-3-oxo-2-(3-oxooctylidene)-4- cyclopenten-lyllheptanoate (8') and other corresponding compounds designated (8 respectively. Example 7 Ethyl 7-]3-ethoxy-5-oxo-2B-(3-oxoocty1)-3- cyclopenten-la-yl]heptanoate (9) A solution of 1.257 g. of ethyl 7-[3-ethoxy-5-oxo-2- (3-oxoocty1idene)-3-cyclopenten-1-yl]heptanoate (8) in 50 ml. of ethanol was hydrogenated at atmospheric pressure in a hydrogenator in the presence of 0. 10 g. of 5 percent rhodium on carbon catalyst. After the solution had absorbed 34.2 ml. of hydrogen, an additional 0.10 g. of catalyst was added and a further 7 ml. of hydrogen was absorbed. The catalyst was removed by filtration followed by removal of the solvent in vacuo. The thus-obtained residue was taken up in methylene chloride and poured onto a chromatographic column containing 100 g. of Florisil (synthetic magnesium silicate) and the column was developed with commercial hexanes containing increasing amounts of acetone. Those fractions exhibiting major ultraviolet absorption near 240 mu (eluted in this instance with 10 percent acetone 90 percent commercial hexanes) were, after evaporation of the solvent, combined to yield 0.929 g. of ethyl 7-[3-ethoxy-5-oxo-2B-(3-oxooctyl)-3- 36 cyelopenten-la-yllheptanoate (9) having the following analysis:

[.R. (principal bands; mineral oil mull): 1,745, 1,700,

1,610 cmf.

N.M.R.: S3 cps (triplet); 243 cps (overlapping quartets); 306 cps (singlet).

In like manner substituting methyl 5-[3-ethoxy-5-oxo-2-(3-oxooctylidene)-3- cyclopentenl -yl]pentanoate, methyl 3-methyl-5-[ 3-ethoxy-5-oxo-2-( 3-oxooctylidene)-3-cyclopentenl -yl ]pentanoate, ethyl 3-[3-ethoxy-5-oxo-2-(3-oxooctylidene )-3- cyclopentenl -yl]propionate, ethyl 7-[3-ethoxy-5-oxo-2-(3-oxobutylidene)-3- cyclopenten-l-yl]heptanoate, and the like, for ethyl 7-[3-ethoxy-5-oxo-2-(3-oxooctylidene)-3- cyclopenten-1-y1]heptanoate is productive of methyl 5-[3-ethoxy-5-oxo-2B-(3-oxooctyl)-3- cyclopenten-1ayl]pentanoate, methyl 3-methyl-5-[3-ethoxy-5-oxo-2B-(3-oxooctyl)-3 -cyclopenten- 1 a -yl ]pentanoate, ethyl 3-[3-ethoxy-5-oxo-2B-(3-oxooctyl)-3cyclopenten-1a-y1]propionate, ethyl 7-[3-ethoxy-S-ox0-2[3-(3-oxobutyl)-3cyclopen ten-la-yl1heptanoate, and the like, respectively.

Similarly substituting other compounds of Formula (8) for ethyl 7-[3-ethoxy-5-oxo-2-(3-oxooctylidene)-3- cyclopenten-l-yl]heptanoate is productive of the corresponding compounds embraced by Formula (9) depending on the starting material used.

Example Ethyl 7-[3-ethoxy-5-oxo-2B-(3-oxooctyl)- 3-cyclopenten-la-yllheptanoate (8) A solution of 10.3 g. of ethyl 7-[3-ethoxy-5-oxo-2-(3 -oxooctylidene)-3-cyclopenten-l-yl]heptanoate (8), 200 ml. of ethanol, and 20 drops of triethylamine was hydrogenated by shaking at a pressure of about 40 psi in a hydrogenator in the presence of 300 mg. of 5 percent palladium on charcoal catalyst. After shaking for 17 hours, the theoretical uptake of hydrogen was complete. The reduction was interrupted and the qualltative ultraviolet absorption was measured in ethanol. The presence of an absorption maximum at 239 mp. and the absence of a peak at 271 my. indicated the reaction to be complete. The catalyst was removed by filtration and the filtrate was concentrated to give a,

residue of 9.83 g.

A total of 12.2 g. of material, prepared as above was dissolved in a minimum volume of 2:1 cyclohexaneethyl acetate and poured onto a chromatographic column containing 1 kg. of silica gel. The column was eluted with 350 ml. fractions of 2:1 cyclohexane-ethyl acetate. The fractions exhibiting ultraviolet absorption near 260 my. (in this instance fractions 17 to 24) were combined and evaporated to give 8.1 g. of ethyl 7-[3- ethoxy-5-oxo-2B-( 3-oxooctyl)-3-cyclopentenl ayllheptanoate (9). The early fractions exhibiting no ultraviolet absorption maxima (in fractions 6-9) were combined and evaporated to give 465 mg. of material exhibiting no ultraviolet absorption above 220 mg, and which was identified as ethyl 7-[3-ethoxy-5-oxo-2B-(3- oxooctyl)cyclopent-la-yllhcptanoate, mg. of whichwas taken up in 0.4 ml. of carbon tetrachloride and placed in an N.M.R.itube. A fine stream of dry hydrogen chloride gas was bubbled through the N.M.R. tube and after about 5 minutes the stream of hydrogen chloride was stopped. The solution contained ethyl 7- [-oxo-2B-(3-oxooctyl)-3-cyclopenten-l(yr-yl]heptanoate which can be isolated by evaporation to dryness. The material so produced can be further purified if desired by chromatography over silica gel in ethyl acetate-cyclohexane 1:10, and combining the fractions exhibiting ultraviolet absorption maxima near 217 my. and N.M.R. at 454 cps (quartet); 361 cps (quartet). Ethyl 7-[5-oxo-2B-( 3-oxooctyl )-3-cyclopenten-l ayl]heptanoate exhibits vasodepressor and lipid mobilizing activity and is useful as an intermediate as described below.

-A mixture of 0.325 g. of ethyl 7-[3-ethoxy-5-oxo-2- (3-oxooctyl)cyclopent-l-yl]heptanoate, 0.30 g. of potassium carbonate in 3.0 ml. of water and ml. of ethanol was heated at reflux under a nitrogen atmosphere for 16 hours. The mixture was cooled and the ethanol removed by concentration in vacuo. The residue was diluted with water and extracted with ether and methylene chloride. The aqueous portion was acidified with dilute hydrochloric acid and then extracted with methylene chloride. Evaporation of the methylene chloride solution to dryness yielded 0.270 g. of 4-butylhexahydro-2,5-dioxo-1-indanheptanoic acid having the following analysis:

LR. (principal bands; methylene chloride): 3,200

2,600 1,750 and 1,720 CITL".

N.M.R.: 580 cps (broad): 141 cps.(broad); 82 cps;

75 cps; 53 cps (distorted triplet). 4-butylhexahydro-2,5-dioxo-l-indanheptanoic acid exhibits vasodepressor and lipid mobilizing activity and is useful in the treatment of hypertension and hyperlipemia in man and other mammals when administered sublingually, intramuscularly, or intravenously in appropriate dosage forms at a dose of 0.002 0.2 'y/kg.

Similarly, substituting ethyl 7-[5-oxo-2B-(3-oxooc tyl)-3-cyclopenten-la-yl]heptanoate for ethyl 7-[3- ethoxy-5-oxo-2B-(3-oxooctyl)cyclopentan-1a-yl]heptanoate in the potassium carbonate step above is also productive of 4-butylhexahydro-2,5-dioxo-2-indanheptanoic acid.

Example 7b Ethyl 7-[5-ethoxy-3 oxo-2B-(3-oxooctyl)- 4-cyclopentenl ayl]heptanoate (9') A solution of 0.450 g. of ethyl 7-[5-ethoxy-3-oxo-2- (3-oxooctylidene)-4-cyclopenten-1-yl]heptanoate (8) in 25 ml. of ethanol was hydrogenated at atmospheric pressure in a hydrogenator in the presence of 0.04 g. of 5 percent rhodium on alumina catalyst. After l hour an additional 0.04 g. of catalyst was added. After the solution had absorbed over l equivalent of hydrogen, the catalyst was removed by filtration and the filtrate was evaporated to give a residue. The residue was dissolved in 5:1 cyclohexane-ethyl acetate and poured onto a chromatographic column containing 30 g. of silica gel and the column was developed with 5:1 cyclohexancethyl acetate, followed by ethyl acetate. The product exhibiting an ultraviolet absorption maximum near 240 my. (in this case obtained in the ethyl acetate eluate) was combined with similar material from a similar reduction and, after removal of the solvent, redissolved in methylene chloride and poured onto a chromatographic column containing 5 g. of Florisil (synthetic magnesium silicate). The column was developed with 10 percent acetone 90 percent commercial hexanes to give the product with ultraviolet absorption maximum near 240 my. (in this case fractions 9 through 14) amounting to 0.094 g. of ethyl 7-[5-ethoxy-3-oxo-2B- (3-oxooctyl)-4-cyclopenten-lat-yl]heptanoate (9).

LR. (principal bands; methylene chloride): 1,735,

1,705 1,690, and 1,595 emf.

N.M.R.: 54 cps (broad triplet), 74 cps (triplet), 84 cps (triplet), 244 cps (overlapping quartets), 304 cps (singlet).

Similarly, substituting other compounds designated (8') i.e., the position isomers of the compounds of Formula (8) for ethyl 7-[5-ethoxy-3-oxo-2-(3-oxooctylidene,4-cyclopenten-l-yl]heptanoate is productive of the corresponding compounds designated (9). Example 8 Ethyl 7-[3-ethoxy-5-oxo-2B-(3-oxooctyl)-3- cyclopenten-l(Jr-yl]heptanoate (9) and ethyl 7-[5- ethoxy-3-oxo-2B-(3-oxooctyl)-4-cyclopenten-layl]heptanoate (9) A solution of 1.599 g. of ethyl 7-[3-ethoxy-5-oxo-2B'- (3-oxooctyl)-3-cyclopenten-lzit-yl]heptanoate (9) and 0.10 g. of p-toluenesulfonic acid in 10 ml. of ethyl alcohol is allowed to stand under an atmosphere of nitrogen at room temperature (20C.) for 66 hours. The solution is then concentrated at reduced pressure on the steam bath to produce a residue. The residue is dissolved in 1:3 ethyl acetate-cyclohexane and poured onto a chromatographic column containing 250 g. of silica gel. the column is eluted with 1:3 ethyl acetatecyclohexane, the fractions being taken in 25 ml. portions until all the material exhibiting ultraviolet absorption near 240 mp. has been eluted. Approximately the first liter eluted contains only traces of oil and is discarded. The remaining fractions consist of varying proportions of ethyl 7-[3-ethoxy-5-oxo-2fi-(3-oxooctyl)-3-cyclopenten-1(Jr-yl]heptanoate (9) and ethyl 7- [5-ethoxy-3-oxo-2B-(3-oxooctyl)-4-cyclopenten-1ayllheptanoate (9').

If desired, the first third and the last third of the above fractions could be further purified by repeated chromatography to give ethyl 7-[3-ethoxy-5-oxo-2B- (3-oxooctyl)-3-cyclopenten-lot-yl]heptanoate (9) and ethyl 7-[5-ethoxy3-oxo-2B-(3-oxooctyl)-4-cyclopenten-la-yl1heptanoate (9) in essentially pure form.

Similarly, substituting other compounds of Formula (9) such as methyl 5-[3-ethoxy-5-oxo-2B-(3-oxooctyl) -3- cyclopentenl a-yl]pentanoate, methyl 3-methyl-5-[3-ethoxy-5-oxo-2B-(3-oxooctyl)-3 -cyclopenten-1a-yl]pentanoate, ethyl 3-[3-ethoxy-5-oxo-2B-(3oxooctyl)-3-cyclopenten-la-yl1propionate, ethyl 7-[3-ethoxy-5-oxo-2B-(3-oxobutyl)-3-cyclopenten-la-yl]heptanoate, and the like, for ethyl 7-[3-ethoxy-5-oxo-2B-(3-oxooctyl)-3- cyclopenten-lot-yl]heptanoate is productive of methyl 5-[3-ethoxy-5-oxo-2B-(3-oxooctyl)-3- cyclopentenl a-yl ]pentanoate and methyl 5-[5-ethoxy-3-oxo-2B-(3-oxooctyl)-4- cyclopenten-la-yllpentanoate, methyl 3-methyl-5-[3-ethoxy-5-oxo-2B-(3-oxooctyl)-3 -cyclopentenl a-yl ]pentanoate and methyl 3-methyl-5-l5-ethoxy-3-oxo-2B-(3-oxooctyl)-4 -cyclopenten-l a-yl ]pentanoate, ethyl 3-[3-ethoxy-5-oxo-2B-(3-oxooctyl)-3-cyclopenten-la-yl]propionate and ethyl 3-[5-ethoxy-3-oxo-2B-(3-oxooctyl)-4-cyclopenten-la-yllpropionate, 

1. A RACEMIC COMPOUND OF THE FORMULA
 2. Racemic ethyl 7-(3-hydroxy-5-oxo-2 Beta -(3-hydroxyoctyl)-cyclopent-1 Alpha -yl)pentanoate.
 3. Racemic dihydro-PGE1. 